Silicon-based phototransistor detectors， offering advantages such as high internal gain， cost-effective and compatibility with CMOS technology， are becoming one of the key devices for large-scale photon integration chip and have significant potential for applications in short-distance optical interconnecting. To relieve its inherent optimization contradiction between responsivity and bandwidth performance， a novel couple ridge waveguide SiGe/Si phototransistor was proposed， in which the carrier transport and the photon propagation were perpendicular and demonstrate the independent optimization on absorption efficiency and operating speed. The optical propagation mode in the SiGe/Si ridge waveguide were analyzed between the single mode and the multiple mode. The geometric parameters of the ridge waveguide to achieve high absorption efficiency were optimized. The ridge waveguide SiGe/Si phototransistor were fabricated using technology compatible with CMOS process platform and achieved a responsivity of 6.4 A/W with the dark current of 10 nA.