Influence of 946 nm dielectric output mirror on single-frequency operation and thermal stability are discussed in detail for the 946 nm laser consisting of thermally bonded Porro prism and corner cube. Degree of linear polarization inside the cavity will not increase significantly by changing the transmittance of p component,while enhancement of the magnetic field applied to the corner cube will not only raise degree of linear polarization inside the cavity efficiently and reduce the output loss,but also decrease the transmittance of p component for the same roundtrip loss difference. Thermal stability and Gaussian beam distribution of this quasi-monolithic non-planar ring cavity are studied by method of propagation matrix.