This paper presents a wireless sensor network security data fusion algorithm which has data integrity and privacy protection. Firstly, using homomorphism encryption algorithm realizes the data privacy; using the key message authentication code based on hash function guarantees the freshness of data; using authentication technique ensures the reliability of information query. Then, CRT theorem is used to test fusion data in sink node and to protect theoretical analysis of the integrity of the data. Finally, the simulation test is made and the results show that the IPPDA algorithm can effectively guarantee the privacy integrity, reliability, and freshness of data, and in the some aspects, such as calculation, traffic and accuracy, etc, the performance of IPPDA algorithm is better than ICPDA and IPDA algorithm.