For a range of issues，including large amount of calculation and low robustness to model variation，existing in the generalized probability data association （GPDA）algorithm，a simplified generalized probability data association（SGPDA） algorithm is proposed，and then SGPDA is combined with strong tracking filter （STF）algorithm to form a novel algorithm named strong tracking filter based on simplified generalized probability data association （SGPDA-STF）. SGPDA greatly reduce calculation without decreasing accuracy. The robustness of STF is strengthened by adjusting the gain matrix. SGPDASTF algorithm combines strong robustness of STF and low calculation cost of SGPDA. The simulation of single observer multiple targets bearings-only tracking in cluttered underwater environment is conducted，and the results show the superiority of SGPDA-STF over the traditional GPDA-EKF algorithm in robustness and calculation cost.