The angle dependence of the self-pumped phase conjugation (SPPO) reflectivity is regarded as a result of the angle dependence of exponential gain TWM in BaTiO3 crystal through measuring and analysing. The theory of double-region coupling of SPPC is explained in detail by using total internal reflection at a corner. It ia pointer that the frequency shift resulted from pump light oscillation between the two interaction regions. The threshold property of forming the SPPC is presented.