In order to solve the extended target tracking algorithm in the case of inaccurate measurement, an ET-CBMeMBer filter algorithm based on box particle filter is proposed.Based on the stochastic set theory, the state set and the set of observations of the extended target are first randomized.Then, based on the interval analysis technique, the multi-extended target pseudo-likelihood function and the potential balance Bernoulli multi-extended target status updating function are deduced out.A fuzzy ART interval measurement set partitioning method suitable for interval measurement is proposed.Then, continuous and steady target tracking is implemented on the basis of the setting of measurement sets.Finally, the simulation experiment is carried out, and the results show the effectiveness of the proposed algorithm.