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Recently, Janus Transition Metal Dichalcogenide (TMD) monolayer MoSSe, with a sandwiched S–Mo–Se structure, has been synthesized by replacing the top S atomic layer in MoS2 with Se atoms. Compared with MoS2, Janus TMDs MoSSe exhibit superior electron mobility as well as enhanced nonlinear optical responses. These characteristics make Janus TMDs highly promising for applications in device fabrication and flexible electronics. Understanding the strain-dependent properties of MoSSe monolayer is fundamentally important to its applications of flexible devices. In this work, we investigated the strain photoluminescence (PL) and angle-resolved second harmonic generation (SHG) responses of a Janus MoSSe monolayer under different uniaxial-strain conditions. Additionally, we used first-principles calculations to investigate the band structure, strain dependence of the SHG susceptibilities and SHG anisotropic patterns. In our PL measurements, applying strain along either the armchair or the zigzag direction causes a red shift in the emission energy, consistent with the band structure simulation results. The SHG measurements show a reduction in SHG intensity under strain applied in different directions.