A device and method for testing a display panel are disclosed. The display panel includes a plurality of pixels arranged in a matrix. Each of the pixels is controlled by a charging gate line and a sharing gate line. The testing circuit includes a first, second, third data testing pad electrically coupling a plurality of red, green, and blue sub-pixels respectively, and k gate testing pad. The sharing gate line of m-th sub-pixel row electrically connects to the charging gate line of (m+2n)-th sub-pixel row, wherein m is a positive integer, and n is the positive integer not less than 2. A row number of the sub-pixel row is divided by k to obtain a remainder q. The q-th gate testing pad electrically connects to the charging gate lines coupled with the sub-pixel row, and k and q are positive integers. And 2n is not divisible by k.