A pratical and novel Nd∶YAG-Cr4+∶YAG laser with dual Q-switching and dual-wavelength output is reported. In the compound resonator couplied with two plano-concave cavities, a single Cr4+∶YAG is both a saturable-absorber of Q-switch at 1.06 μm laser from Nd∶YAG and a laser gain medium at 1.44 μm with 1.06 μm laser as its intra-cavity pump source. the dual-wavelength laser oscillation with passively Q-switched 1.06 μm laser and gain-switched 1.44 μm laser is realized in the laser. The output energy and pulse duration of 1.06 μm and 1.44 μm laser are 18 mJ, 52 ns and 0.2 mJ, 19 ns respectively, and the pulse duration of the latter is about one of third of the former. The working mechanism of the dual Q-switching is analyzed in theory according to energy levels of the Cr4+∶YAG and the feature of the compound resonator. Based on the rate equations, the relationship between pulse duration of 1.44 μm laser and the intra-cavity power of 1.06 μm laser is derived. The theoretical data (21.7 ns) of pulse duration of 1.44 μm laser is roughly consistent with the experimental resultt (19 ns).