A particle detecting module is provided and includes a base, a piezoelectric actuator, a driving circuit board, a laser component, a particulate sensor and an outer cover. A gas-guiding-component loading region and a laser loading region are separated by the base. By the design of the gas flowing path, the driving circuit board covering the bottom surface of the base, and the outer cover covering the surfaces of the base, an inlet path is defined by the gas inlet groove of the base, and an outlet path is defined by a gas outlet groove of the base. Consequently, the thickness of the particle detecting module is drastically reduced.