Step-shaped spur dike is widely used in waterway regulation，but its flow structure is still not fully studied. Based on the PIV indoor flume test，we discuss the distribution of dimensionless longitudinal time average velocity u+，turbulence intensity T+u，Reynolds stress R+ and turbulent kinetic energy E+ in the stepped spur dike area. The results show that the longitudinal section of spur dike flow can be divided into downstream area，reflux area and transition area. The high velocity area of u+for each profile from the inside of spur dike to the head of the first step spur dike is located in the upper part of the dam crest，while the low velocity area and the reflux area are located in the lower part of the dam crest，the u+ of section outside spur dike variation first increases and then decreases. Affected by the flow over the dam crest，T+u of vertical line upstream of spur dike change obviously with y+，while T+u of vertical line downstream of spur dike change relatively gentle with y+. The high value area of R+ is located near the dam crest and is in a strip shape. When the discharge is small，the vertical change of R+ with y+ is relatively gentle，and the distribution curve of R+ near the dam crest is in “S” shape. The change of R+ in the upstream of spur dike is intensified with the increase of discharge. The high value area of E+ diffuses from the top of the dam to the bottom of the flume and water surface in a triangular shape，and E+ increases with the increase of discharge.