Microencapsulated phase change materials have excellent ability to store energy and resist the leakage of phase change materials during the solid-liquid phase change process. Traditional mechanical agitation emulsification method has intrinsic difficulty in preparing phase change microcapsules with uniform and controllable particle size. In this work, premix membrane emulsification was employed to prepare emulsion, and liquid paraffin/melamine-formaldehyde resin microcapsules with narrowed particle size dispersion were successfully prepared by taking advantages of the combination of premix membrane emulsification and in?situ polymerization. The result showed that transmembrane pressure and passes had a great effect on particle sizes and distributions of the resulting microcapsules. And the particle sizes and distributions of microcapsules can be effectively controlled by adjusting the transmembrane pressure and passes. When SPG (Shirasu Porous Glass) membrane with an average pore size of 10.1 μm was used, the liquid paraffin microcapsules with narrowest particle size distribution can be obtained by using transmembrane pressure of 0.2 MPa and transmembrane pass of 4 times. And these microcapsules had an average particle size of 10.84 μm and a relative standard deviation of 0.16. But the relative standard deviation of the particle size of the microcapsules prepared by using the combination of mechanical agitation emulsification and in?situ polymerization was 0.89. It indicated that microcapsules with a narrower particle size distribution can be synthesized effectively by employing the premix membrane emulsification. The surfaces of the microcapsules were smooth and dense, and without any adhesion and reunion. They exhibited excellent heat resistance and cold/heat cycle stability, and the encapsulation ratio was about 80%. Besides, the preparation efficiency of the paraffin microcapsules was greatly improved by using the methods of premix membrane emulsification coupled with in?situ polymerization. These results indicated that the combination of premix membrane emulsification and microencapsulation technology was a promising candidate for the preparations of low temperature alkane phase change microcapsules with narrowed size dispersion.