[Solved]-after using for loop all my column graphs are plotted in single color i need each bar in different color in highcharts-Highcharts

set the colorbypoint option to true and define the color sequence that you want.

options = {
chart: {...},
plotoptions: {
    column: {
        colorbypoint: true
    }
},
colors: [
    '#ff0000',
    '#00ff00',
    '#0000ff'
]}

maybe you are using same configuration object for all of your charts created in a loop.

const colors = highcharts.getoptions().colors
const option = {
  series: [{
    data: [29.9, 71.5, 106.4, 129.2, 144.0, 176.0, 135.6, 148.5, 216.4, 194.1, 95.6, 54.4],
    type: 'column',
    color: colors[0]
  }]
}
const options = []
for (let i = 0; i < 4; ++i) {
  option.series[0].color = colors[i]
  options[i] = option
    //options[i] = json.parse(json.stringify(option)) // clone object
}
for (let i = 0; i < 4; ++i) {
  highcharts.chart('chart' + i, options[i])
}

live example: https://jsfiddle.net/q7x1lecg/