You can also find many tutorials by typing "qt charts" in Youtube.

both series objects are connected to same data source

Does that mean that both series display the same data ?
In this case maybe you see only one series in your chart because serires2 is hidden under series1 ?

// I have defined QChart object 
QValueAxis *AxisX=new QValueAxis;
axisX->setRange(0,2000);
axisX->setLableFormat("%g");
axisX->setTitleText("Samplees");

QValuesAxis *axisY=new QValueAxis;
axisY->setRange(-1,1);
axisY->setTitleText("Audio level");


chart->setAxisX(axisX,series);
chart->setAxisY(axisY,series);
chart->setAxisX(axisX,series2);
chart->setAxisY(axisY,series2);



// I have two dynamic QLineSeries objs those are series and series2 have defined them and now I want to plot them on the chart, In this series2 is not getting plotted on the chart, there is no lose or empty data on the series2, both series objects are connected to same data source,
//chart is displaying only series object data.

So, Is there any mistakes in the setAxes to the chart?

The advantage of QValueAxis is that you can customize the axis according to your need, by changing font, colors, tick count, (see also AbstractAxis properties), etc... But usually createDefaultAxes() will make the job.

Personnaly I have used it only to make the font smaller for displaying on Mobile.

Here is a simple example:

 ChartView{
    //...    
    LineSeries {
        //...
        axisY: ValueAxis{
            labelsFont.pointSize: 8
            color: "blue"
            labelsAngle: 20
        }
    }
 }