In situ composites containing a thermotropic liquid crystalline polymer were prepared by polycondensation of 1,4-bis(p-hydroxy-benzoyloxy)butane with 2-bromoterephthaloyl chloride in a poly(methyl methacrylate) solution. Morphology and mechanical, thermal properties of the composites were examined by differential scanning calorimeter(DSC), dynamic mechanical thermal analyser(DMTA), optical microscope and scanning electron microscope(SEM). The TLCP domains showed nematic phase. The glass transition temperature(T_g) and mechanical properties of the PMMA in the composites increased with increasing the content of TLCP. The TLCP domains were finely dispersed in the PMMA matrix. The 20 wt% TLCP/PMMA composite prepared by in situ polymerization showed more improved mechanical property with finely well dispersed morphology compared with that prepared by solution blending of the same composition.