效果

换行前

换行后

核心代码 

word-wrap: break-word;

或 

word-break: break-all;

 完整代码demo

<template>
	<view>
		<view class="all_style">
			<view class="line1">
				aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa
			</view>
		</view>
	</view>
</template>

<script>
	export default {
		data() {
			return {

			}
		},
		onLoad() {

		}
	}
</script>
<style>
	.all_style {
		width: 500rpx;
		height: 500rpx;
		border: 1px solid black;
	}

	.line1 {
		/* 长单词或字符串自动进行换行，下面两个二选一即可 */
		/* word-wrap: break-word; */
		word-break: break-all;
	}
</style>