Detecting weak moving targets is an important task for digital television terrestrial broadcasting (DTTB) based passive radar. The cross ambiguity function (CAF) suffers from the range and Doppler frequency migrations caused by the velocity and acceleration of the targets. The integration gain can’t increase anymore. A new detector is proposed for this problem. In this detector, the fractional Fourier transform (FRFT) is used to compensate the Doppler frequency migration, and the Hough transform is utilized to accumulate the echo of the moving targets during the long integration time. The block diagram and the procedure of this detector are given. Simulation results show that the proposed method can detect weak moving targets effectively.