先贴上代码：

# -*- coding: utf-8 -*-

# Form implementation generated from reading ui file 'json_converter.ui'
#
# Created by: PyQt5 UI code generator 5.15.9
#
# WARNING: Any manual changes made to this file will be lost when pyuic5 is
# run again.  Do not edit this file unless you know what you are doing.


from PyQt5 import QtCore, QtGui, QtWidgets
from PyQt5.QtWidgets import QApplication
import json
import sys

class Ui_Form(object):
    def __init__(self):
        super().__init__()    

    def setupUi(self, Form):
        Form.setObjectName("JSON Viewer")
        Form.resize(1265, 725)
        
        self.label = QtWidgets.QLabel(Form)
        self.label.setObjectName("label")
        self.label.setGeometry(QtCore.QRect(10, 20, 72, 15))


        self.lineEdit = QtWidgets.QLineEdit(Form)
        self.lineEdit.setObjectName("lineEdit")
        self.lineEdit.setEnabled(True)
        self.lineEdit.setGeometry(QtCore.QRect(90, 20, 1061, 21))
        self.lineEdit.setReadOnly(True)

        self.toolButton = QtWidgets.QToolButton(Form)
        self.toolButton.setObjectName("toolButton")
        self.toolButton.setGeometry(QtCore.QRect(1160, 20, 47, 21))
        self.toolButton.clicked.connect(self.getJSONFile)

        self.tableView = QtWidgets.QTableView(Form)
        self.tableView.setGeometry(QtCore.QRect(10, 60, 1241, 611))
        self.tableView.setObjectName("tableView")
        self.tableView.horizontalHeader().setVisible(True)

        self.convertButton = QtWidgets.QPushButton(Form)
        self.convertButton.setObjectName("convertButton")
        self.convertButton.setGeometry(QtCore.QRect(10, 680, 93, 28))        
        self.convertButton.clicked.connect(self.loadJsonFile)

        self.pushButton = QtWidgets.QPushButton(Form)
        self.pushButton.setObjectName("pushButton")
        self.pushButton.setGeometry(QtCore.QRect(1160, 680, 93, 28))        
        self.pushButton.clicked.connect(Form.close)



        self.retranslateUi(Form)
        QtCore.QMetaObject.connectSlotsByName(Form)
        
    def retranslateUi(self, Form):
        _translate = QtCore.QCoreApplication.translate
        Form.setWindowTitle(_translate("JSON Viewer", "JSON Viewer"))
        self.pushButton.setText(_translate("Close", "Close"))
        self.label.setText(_translate("JSON File","JSON File"))
        self.convertButton.setText(_translate("Load JSON File","Load JSON File"))
    
        
    def setColumnHeader(self, columnHeader):
        self.model=QtGui.QStandardItemModel()
        self.model.setHorizontalHeaderLabels(columnHeader)                
        self.tableView.horizontalHeader().setModel(self.model)
        

    def show(self, Form):
        Form.show()
    
    def close(self, Form):
        Form.close
           
    def addTableLine(self,row):
        item=[]
        for i in range(len(row)):
            item.append(QtGui.QStandardItem(row[i]))

        self.model.appendRow(item) 
        self.tableView.setModel(self.model)
    
    def getJSONFile(self):
        fname=QtWidgets.QFileDialog.getOpenFileName(caption="Open file", directory="",filter="Json files (*.json)")        
        self.lineEdit.setText(fname[0])
    
    def loadJsonFile(self):
        fname=self.lineEdit.text()
        f=open(fname,encoding="utf-8")
        header_list=[]
        data=json.load(f)
        f.close

        for i in data['data'][0]:
            header_list.append(i)

        self.setColumnHeader(header_list)
        for i in data['data']:
            item=[]
            for j in i:
                item.append(QtGui.QStandardItem(i[j]))
            self.addTableLine(item)

if __name__ == "__main__":
    app = QApplication(sys.argv)
    Form=QtWidgets.QWidget()    
    main_win = Ui_Form()    
    main_win.setupUi(Form)
    main_win.show(Form)

    sys.exit(app.exec())        
   

项目运行时的截图：

这个项目使用Qt Designer创建的。