A display panel and a testing method of the display panel are provided. The display panel has a display region and a non-display region and includes a first substrate, a second substrate, and a display medium. The display panel further includes scan lines, data lines, pixel units, at least one testing line, and at least one testing pad. The scan lines and the data lines are located on the first substrate within the display region. The pixel units are located on the first substrate within the display region. Each pixel unit electrically connects one of the scan lines and one of the data lines. The testing line is located on the first substrate within the non-display region, crosses over the scan lines, and is insulated from the scan lines. The testing pad is located on the first substrate within the non-display region and electrically connected to the testing line.