Abstract: Type-B sleeve repair is one of the main permanent repair methods for long-distance oil and gas pipelines at present. However, fillet weld defects are often produced during the operation, which need to be detected and evaluated by phased array ultrasonic method. In order to further study the capability of phased array ultrasonic testing method in detecting the defects in the fillet weld of type-B sleeve, the calculation model of phased array testing for fillet weld of type-B sleeve was established with the developed ultrasonic numerical simulation program, and the simulation on propagation sound field, testing signal and image of phased array ultrasonic in fillet weld of type-B sleeve was realized. On this basis, the detection capabilities of different phased array ultrasonic testing methods for defects at different positions in the weld were compared and analyzed. Finally, the simulation results were verified by experiments. The research results could provide theoretical basis and technical means to optimize the phased array ultrasonic testing method for weld of type-B sleeves.