There are fewer researches on the effect of functional group position change on device performance for highly efficient perovskite solar cell. In this work, we take pyridinesulfonic acid as an example, and study the effect of the isomeride: 2- and 3-pyridinesulfonic acid self-assembled monolayer on device performance for highly efficient perovskite solar cell. The efficiency of control device is 14.65% (Hysteresis Index = 0.31) under illumination of a simulated sunlight (AM 1.5 G, 100 mWcm(-2)). Through use of the 3-pyridinesulfonic acid self-assembled monolayer, the device exhibits striking improvements to reach the efficiency of 16.88% (Hysteresis Index = 0.02), which constitutes an enhancement compared to those of 2-pyridinesulfonic acid self-assembled monolayer modified device (16.54%, Hysteresis Index = 0.02). The enhanced photovoltaic performances can be attributed to the larger perovskite grain sizes, and easier passivation of electron transporting layer/ perovskite interface, which promote the charge separation, transport and collection.