With the improvement of technology, more cores are placed on a single chip to form a system. The volumes of test data becomes a challenges for circuits test. The paper presents a test data compression which uses hybrid prefix code and a new test set regenerating algorithm. In essence, the technique uses two formats of prefix to encode for the new regenerated test set, and the regenerated test set is better suitable to our compression scheme. So it gain better compression ratio. Experimental results show that the proposed compression solution could re duce test data volume effectively with a simple decoding architecture.