A parameter x is introduced to characterize the strength of thermal lens spherical aberration, whose influences on resonator's stable zones are analyzed theoretically. Some new and helpful results are obtained. For symmetrical plane-plane cavity, spherical aberration has just influence on the back edge of stable zone. For asymmetrical plane-plane cavity, spherical aberration has influence on the back edges of the two stable zones and the front edge of the second stable zone. Effects of transverse mode collapsing to TEM00 mode and stable zones separation of different order's transverse modes are pointed out, which is the foundation of TEM00 mode output power scaling for solid state laser oscillator. Influences of parameters such as resonator's long arm length, short arm length, and pump beam radius on the extent to which of stable zones separation of different order transverse modes are discussed. An experimental setup of a high power diodes dual-end pumped Nd:YVO4 TEM00 mode laser oscillator is built up and investigated experimentally. 51.2 W TEM00 mode output power in CW operation is achieved with an optical-to-optical efficiency of about 50% and beam quality factor M2 being 1.2.