[Solved]-highcharts line graph with ajax-Highcharts

You need to correct your mapping function, for example:

var response = {
    "date": ["13:00:00", "13:00:01", "13:00:02", "13:00:03", "13:00:04"],
    "count": ["1", "2", "3", "4", "2"]
};

new_data = $.map(response.date, function(el, index) {
    return {
        name: el,
        y: parseInt(response['count'][index])
    };
});

Additionally, with that data structure, I recommend you to use category axis type.

xAxis: {
    ...,
    type: 'category'
}

Live demo: http://jsfiddle.net/BlackLabel/ptx6fy2q/

API Reference: https://api.highcharts.com/highcharts/xAxis.type