Abstract: An algorithm for acquiring weak signal of Compass-1 is presented. The benefits of Compass-1 signal include two-fold, the first one is that the two-beam signals are transmitted by the satellite at the same frequency, the second one is the prior knowledge of the synch word and the end word of the continues sequence. In so doing, a long period of joint coherent acquisition can be conducted to increase the capture sensitivity by increasing the captured signal power, and also reducing the loss of non-coherent accumulation. Simulation and experimental results show that the joint acquisition method can capture the signal below -133 dBm, which is superior to the single-beam serial search acquisition method.