Spin transfer torque magnetic random access memory (STT-MRAM) is a potential candidate for next generation universal memory technology, which possesses the high density and cost benefits of DRAM, the high access speed of SRAM, the non-volatility of Flash, compatibility with CMOS and essentially unlimited endurance. However, STT-MRAM commercialization is hampered by the reliability issues, especially its poor thermal reliability. Generally, the elevated ambient temperature and Joule heating cause the thermal reliability issues of STT-MRAM. These effects result in many failures such as data cannot be written into the cell or read out from the cell correctly. Therefore, reliability issues of STT-MRAM has long been the design challenge under thermal fluctuation due to their thermal sensitivity property. In the paper, a series of simulation experiments are carried out to evaluate the reliability and performance of STT-MRAM in terms of operation error rate, delay and energy consumption. These simulation experiments are performed in Cadence with a compact spice model of PMA (Perpendicular Magnetic Anisotropy) MTJ (Magnetic Tunnel Junction), which is developed by our group and used widely. The information obtained from these experiments would provide foundation for probing the enhancing strategies of reliability and performance for STT-MRAM.