The present disclosure provides a GPU-based third-order low-rank tensor completion method. Operation steps of the method includes: (1) transmitting, by a CPU, input data DATA1 to a GPU, and initializing the loop count t=1; (2) obtaining, by the GPU, a third-order tensor Yt of a current loop t based on the least squares method; (3) obtaining, by the GPU, a third-order tensor Xt of the current loop t based on the least squares method; (4) checking, by the CPU, whether an end condition is met; and if the end condition is met, turning to (5); otherwise, increasing the loop count t by 1 and turning to (2) to continue the loop; and (5) outputting, by the GPU, output data DATA2 to the CPU. In the present disclosure, in the third-order low-rank tensor completion, a computational task with high concurrent processes is accelerated by using the GPU to improve computational efficiency.