[Solved]-Highcharts highlight single point on line-Highcharts

using a marker we can do this:

$(function () {
    $('#container').highcharts({
        chart: {
        },
        xaxis: {
            categories: ['jan', 'feb', 'mar', 'apr', 'may', 'jun', 'jul', 'aug', 'sep', 'oct', 'nov', 'dec']
        },



        series: [{
            data: [29.9, { marker: {
                    fillcolor: '#ff0000',
                    linewidth: 3,
                    linecolor: "#ff0000" // inherit from series
            },y:71.5}, 106.4, 129.2, 144.0, 176.0, 135.6, 148.5, 216.4, 194.1, 95.6, 54.4]        
        }]
    });
});

http://jsfiddle.net/zr4kn/