The negative skin friction(NSF) has an important influence on the bearing and deformation behavior of piles in collapsible loess soils. The current calculating method of NSF recommended by the Standard for Building Construction in Collapsible Loess Regions (Standard I) and the Technical Code for Building Pile Foundations (Standard II) cannot reflect the actual behavior of the NSF. This paper conducted a statistical analysis on the field flooding test datum of reinforced concrete piles in the loess area of China in the past 30 years. The relationship between the depth of the neutral plane, the depth of the maximum NSF as well as the coefficient of NSF with the pile length diameter ratio was analyzed, and empirical expressions of the neutral plane depth ratio, the maximum NSF depth ratio as well as the NSF coefficient with the pile length diameter ratio were obtained by linear fitting, then a new approach for calculating NSF of piles in loess soils was established. According to the new method, the distribution of the NSF along pile shaft is represented by a triangle, i.e., the NSF increases with the depth and reaches a maximum value at a certain depth, then decreases to zero at the neutral plane depth, which perfectly reflects the actual distribution characteristics of the NSF along pile shaft. The calculated NSF by using the new method presented herein, Standard I and Standard II were compared with the field test datum. The results show that the neutral plane depth ratio predicted by Standard II is better than that predicated by Standard I, and the maximum drag load predicted by Standard I is better than that predicated by Standard II, while the NSF calculated by the new approach are in good agreement with the measured results.