With the characteristics of high energy storage density, constant temperature in phase change process and convenient storage/transportation, the microencapsulated phase change material (MPCM) has a broad application prospect in the fields of thermal storage, transportation and utilization such as solar energy thermal utilization, waste heat recovery and utilization, refrigeration and air conditioning, and so on. However, the traditional MPCM particles use formaldehyde as the shell material, which releases harmful substances during application process. In addition, the MPCM application fields is restricted because of low thermal conductivity of polymer shell. Therefore, it is necessary to develop a new type of formaldehyde-free MPCM. In this work, the MPCM particles of n-dodecanol as core material and acrylic resin copolymers as shell were prepared employing the method of suspension polymerization under the condition of ultrasound exposure. Furthermore, in order to enhance the thermal performance of MPCM particles, the graphene oxide (GO) was introduced to modify the MPCM. Then the characteristics of MPCM and GO-MPCM were tested by scanning electron microscope (SEM), Fourier transform infrared spectrometer (FT-IR), differential scanning calorimetry (DSC), thermal gravimetric analyzer (TG–DTA). The results showed that there was no effect on basic chemical organization of MPCM with introduce the graphene oxide nano-particles. However, under the same preparation conditions, the introduction of graphene oxide nano-particles increased the MPCM particles size and greatly affected their appearance and morphology. The thermal conductivity of MPCM particles was improved. The encapsulation rate increased to 62%, and the latent heat of phase change was 135.6 kJ/kg, which was 45% higher than that of unmodified phase change microcapsules. The study results in this work can provide data support for the preparation and performance improvement of MPCM particles, and also provide theoretical basis for its engineering application.