Abstract: The paper is about validating the theoretical calculations of sub-critical reactivity and dynamic characteristic measurements in different sub-critical levels by using external neutron source ²⁵²Cf on VENUS-Ⅱ. By using the source-jerk method on VENUS-Ⅱ, the measurement theory of sub-critical reactivity, experimental assembly, measurement system, reactor core, experiment results and so on were introduced. Three sub-critical levels (k_eff is 0.99, 0.98 and 0.97) were chosen to carry out the measurements by different loadings of nuclear fuel rods. The theoretical calculation result fits well with the experimental measurement result, which proves the correctness of calculation result. The theoretical calculation code and nuclear data validated by experiment can provide a reference value to the sub-critical reactor design of the advanced nuclear fission ADS in the future.