Poly(methyl methacrylate)/poly(styrene-acrylonitrile) (PMMA/SAN) displays a lower critical solution temperature (LCST)-type phase behavior, in which the miscibility of the binary system is determined by the phase-separation temperature. Herein, a PMMA-type comb-like polymers, which are constituted by PMMA backbone and side chains and a few randomly distributing epoxide groups along the backbone are applied as compatibilizers in an immiscible acrylonitrile-butadiene-styrene/poly(L-lactic acid) (ABS/PLLA) system and it has been found that the stability of the PMMA-type compatibilizers at the interface of the immiscible blend is determined by the processing temperature. When the processing temperature is inside the miscible region of the phase diagram, the PMMA-type compatibilizers can hold the interface of PLLA and ABS phase tightly, with the PMMA backbone and side chains entangling with the SAN phase of ABS and the grafted PLLA side chains with the PLLA phase and the obtained compatibilized PLLA/ABS blend exhibits excellent toughness compared to the neat PLLA. Otherwise, the compatibilizers tend to be drawn into the PLLA phase to form micelles, due to the weakening interactions of PMMA chains with the SAN phase when the temperature is outside the miscible region. These results on one hand indicate the importance of the force balance for the compatibilizers at the interface, and on the other hand reveal the effect of temperature in a multicomponent system which contains temperature-sensitive polymeric pairs.