[Solved]-How do I format x-axis label in highcharts-Highcharts

Cool, try this:

Add this formatter to your xAxis labels object:

xAxis {
    ...
    labels: {
        ...
        formatter: function() {
            return this.value.toString().substring(0, 6);
        },
    }
}

Link: http://jsfiddle.net/tn6Kw/9/