Single nucleotide polymorphism (SNP) rs17849071 was recently reported to be inversely associated with PIK3CA amplification in follicular thyroid cancer, but the main function of this SNP remains unclear. In this study, by using PCR and sequencing method, we explored whether this SNP was associated with P53 expression status and other clinicopathological characteristics in 62 Chinese breast cancer (BCa) patients. In our results, P53 protein accumulation was significantly associated with HER2 overexpression (P = 0.013) and Ki-67 expression (P = 0.007), which were in accord with previous studies. Besides, there was a significantly inverse relationship between P53 protein expression and rs17849071 GT+GG genotype in Chinese BCa patients (P = 0.044). The SNP was not related to other important BCa markers such as estrogen receptor, progestin receptor, and HER2. Among different BCa intrinsic subtypes, no significant differences were found on P53 expression status (P = 0.356) or rs17849071 polymorphism (T>G) (P = 0.813). In conclusion, SNP rs17849071 GT+GG genotype was inversely associated with P53 protein accumulation in BCa samples. Studies with larger sample size focusing on exploring the relationship of rs17849071 polymorphisms, P53 accumulation, P53 mutations, and PIK3CA amplification might be needed.