思路：使用markpoint

option = {title: {text: 'Rainfall vs Evaporation',subtext: 'Fake Data'},tooltip: {trigger: 'axis'},legend: {data: ['Rainfall', 'Evaporation']},toolbox: {show: true,feature: {dataView: { show: true, readOnly: false },magicType: { show: true, type: ['line', 'bar'] },restore: { show: true },saveAsImage: { show: true }}},calculable: true,xAxis: [{type: 'category',// prettier-ignoredata: ['Jan', 'Feb', 'Mar', 'Apr', 'May', 'Jun', 'Jul', 'Aug', 'Sep', 'Oct', 'Nov', 'Dec']}],yAxis: [{type: 'value'}],series: [{name: 'Rainfall',type: 'bar',data: [2.0,14.9, 7.0, 23.2, 25.6, 76.7, 135.6, 162.2, 32.6, 20.0, 6.4, 13.3],markPoint: {silent: true,label: {show: false},symbol:'diamond',symbolSize: [45,10],itemStyle: {borderColor: '#000'},data: [{coord: ['Jan',2]},{coord: ['Feb',14.9]},{coord: ['Mar',7]},{coord: ['Apr',23.2]},{coord: ['May',25.6]},]},markLine: {silent: true,// label: {show: false},// symbol:'diamond',// symbolSize: [45,10],// itemStyle: {//   borderColor: '#000'// },// data: [//   {coord: ['Jan',2]},//   {coord: ['Feb',14.9]},//   {coord: ['Mar',7]},//   {coord: ['Apr',23.2]},//   {coord: ['May',25.6]},// ]},},]
};

option = {title: {text: 'Rainfall vs Evaporation',subtext: 'Fake Data'},legend: {data: ['Rainfall', 'Evaporation']},calculable: true,xAxis: [{type: 'category',// prettier-ignoredata: ['Jan', 'Feb', 'Mar', 'Apr', 'May', 'Jun', 'Jul', 'Aug', 'Sep', 'Oct', 'Nov', 'Dec']}],yAxis: [{type: 'value'}],series: [{name: 'Rainfall',type: 'bar',data: [2.0,14.9, 7.0, 23.2, 25.6, 76.7, 135.6, 162.2, 32.6, 20.0, 6.4, 13.3],markPoint: {silent: true,label: {show: false},symbol:'diamond',symbolSize: [45,10],itemStyle: {borderColor: '#000'},data: [{coord: ['Jan',2]},{coord: ['Feb',14.9]},{coord: ['Mar',7]},{coord: ['Apr',23.2]},{coord: ['May',25.6]},]},markLine: {silent: true,label: {show: false},symbol: 'none',lineStyle: {type: 'solid',color: new echarts.graphic.LinearGradient(0, 0, 0, 1,[{offset: 0, color: 'rgba(0, 0, 0,1)'},{offset: 1, color: 'rgba(0, 0, 0,0.5)'}])},data: [{xAxis: 'Jan' },{xAxis: 'Feb' },{xAxis: 'Mar' },{xAxis: 'Apr' },]}},]
};