[en] The effects of power density, pulse repetition frequency, duty cycle and microwave irradiation time on grindability and crushability of breccia type uranium ore are investigated by a self-developed pulsed microwave device with a mean power of 50 kW and a frequency of 2450 MHz. The experimental results show that the grindability and crushability of the ore gained the greatest increase when the pulse repetition frequency is 500 Hz,the duty cycle is 0. 5, the irradiation time is 12 s,and the microwave power is 50 kW. The mechanical strength is decreased by 43.38% and the grindability is increased by 41.20%. In order to reveal the mechanism involved, the particle flow code software PFC2D developed by ITASCA is employed to establish a two-dimensional model with quartz being gangue minerals and uraninite being ore mineral. PFC2D analysis shows that the microcracks is induced by the pulsed microwave pre-treatment in the ore that resulted in the grindability and crushability of breccia type uranium ore; and the quantity of microcracks is reached to the most in the ore pretreated by the pulsed microwave when the power density is 5 × 10⁸ W/m³, the microwave irradiation time is 12 s, the pulse repetition frequency is 500 Hz, and the duty cycle is 0.5. Therefore, when pulsed microwave pretreatment is used for the processing of the ore, the key factor is to match the parameters of the pulsed microwave with the uranium ore to increase its grindability and crushability. (authors)