The wear particle monitoring technology has become a key part of the intelligent diagnosis of aero-engine, because the wear of rotating parts of aero-engine is an important factor that affects the lifespan of aero-engine. The parameters of the wear particle in the lubricating oil can directly reflect the wear state of rotating parts. In this article, a comb type capacitance sensor is proposed, which uses the structure of built-in multi-parallel plate electrodes. On the basis of analyzing the wear particle detection principle of the sensor, we determine the structural optimization direction and the optimal parameter through numerical simulation. Experimental results show that when the diameter of iron wear particles increases from 0. 3 mm to 0. 9 mm, the variation in capacitance increases from 3 Ff to 17 Ff. When the number of wear particles increases from 1 to 4, the variation in capacitance is approximately in a positive linear relationship with the particle number, and the maximum increase ratio is about 200% to 350% . When the power frequency increases from 10 kHz to 100 kHz, the drop ratio of variation in capacitance is 36% to 67% . The results show that the comb type capacitive sensor can improve the uniformity of the internal electric field, which could improve the consistency of the results and the detection rate of wear particles, and detect 200 μm diameter particles in 10 mm diameter pipe which shows a good discrimination in outcome. This technology can provide technical support for the monitoring research of aero-engine oil wear particles.