Abstract: Determination of the working status of RDS circulating valve via operation parameters analysis and disassembly inspection after pulling out the test string suffers from indirectness and hysteresis. Moreover, full-cycle downhole pressure and temperature data collected by APR testing technology have not been fully utilized for valve condition diagnosis. According to the operating principle of RDS circulating valve, surface tubing pressure, downhole pressure and temperature datasets from 10 wells successfully operated with APR tests in the Sichuan Basin over past two years were screened. With the final pump shutdown defined as the reference point, the bottomhole pressure variation rate after ball valve closure (0.1–100 MPa/h during continuous pressure drop stage and 1–100 MPa/h during slight pressure build-up stage), hysteretic bottomhole temperature response (decrease followed by increase) for each well, and rapid short-term rise of surface tubing pressure were extracted to construct a characteristics chart of downhole pressure and temperature under normal operating conditions. This chart was applied to two field wells with abnormal conditions. Diagnosis results indicate that tubing-casing communication in Well YANT1 originates from premature opening of the hydraulic bypass, which passively opens the RDS circulating valve, whereas incomplete ball valve closure occurs in Well PY102. This study provides supporting evidence for field fault diagnosis. The proposed chart offers a quantitative criterion for real-time identification of RDS circulating valve performance during APR testing in the Sichuan Basin and possesses practical engineering significance.