We explored Q-switching mechanism for the newly proposed Tm/Ho composite laser via developing a hybrid resonator for separating the intra-cavity Tm laser modulated by the saturable absorber (SA). With a Cr:ZnSe SA, successful passively Q-switching process with the maximum average output power of 474 mW and the shortest pulse width of 145 ns were obtained at the pulse repetition frequency of 7.14 kHz, where dual wavelength oscillation in both 2090 nm and 2097 nm was observed. This work provides an effective way for a direct laser diode (LD) pumped Q-switched Ho laser, which is compact and accessible. Furthermore, the current SA could be replaced by the 2D materials with broadband saturable absorption such as topological insulators or transition-metal dichalcogenides for seeking novel PQS lasers.