This paper presents a fuzzy mathematic model for data association applying to the passive sensor network and defines the fuzzy synthetic closeness.Based on the fuzzy synthetic closeness

a fuzzy track initiation algorithm is proposed.The selection of the starting points for searching in the steepest descent algorithm

the initial state estimation of the candidate targets

and the methods for target detection and multivalency processing are also discussed.The advantage of the proposed algorithm over the algorithms available is that it isnt necessary to know the distributed characteristic of the clutter and the detection probability of target.Simulation results show the proposed algorithm can initiate the tracks effectively.