要限制可选行数，可以使用gridOptions属性的rowSelection属性。将rowSelection设置为“multiple”以允许多行选择。然后，使用gridOptions.onSelectionChanged事件来捕获当前选择的行数。最后，使用gridApi.deselectAll()方法来取消选择所有行。

以下是代码示例：

import React, { Component } from 'react';
import { AgGridReact } from 'ag-grid-react';

class MyGrid extends Component {
  constructor(props) {
    super(props);

    this.state = {
      rowData: [],
      selectedRow: null
    };

    this.gridOptions = {
      rowSelection: 'multiple',
      onSelectionChanged: this.onSelectionChanged.bind(this)
    };

    this.columnDefs = [
      {headerName: "Make", field: "make"},
      {headerName: "Model", field: "model"},
      {headerName: "Price", field: "price"}
    ];
  }

  componentDidMount() {
    fetch('https://api.myjson.com/bins/15psn9')
      .then(result => result.json())
      .then(rowData => this.setState({rowData}));
  }

  onSelectionChanged() {
    const { api } = this.gridOptions;
    const selectedRows = api.getSelectedRows();
    if (selectedRows.length > 3) {
      api.deselectAll();
      alert("不能选择超过3行！");
    } else {
      this.setState({selectedRow: selectedRows[0]});
    }
  }

  render() {
    const { rowData, selectedRow } = this.state;

    return (
      

        
        {selectedRow ? (
          

            

            
Selected: {selectedRow.make} {selectedRow.model}
          
        ) : null}
      
    );
  }
}

export default MyGrid;