The embodiments of the present disclosure provide a transparency overlay method for a virtual set top box, a virtual set top box and a storage medium. Transparency layout features of a picture presented by an application scenario of the virtual set top box are acquired; whether compression processing of transparency data is allowed for each block on the picture is determined according to the transparency layout features; and compression processing of transparency data is performed on each allowed block, and transparency overlay is performed according to transparency data sampling points less than full number of transparency data sampling points in each allowed block.