Abstract: The source term and dose analysis model in loss of coolant accident (LOCA) was established and the effect of core release time, spray function and precursor nuclide decay on the source term and radiological consequence was studied. The results show that the cumulative activity released to environment in case of core instantaneous release is larger than that in case of core sustained release, especially for the short half-life radionuclides, such as ¹³⁵Xe^m and ¹³⁸Xe. In the early time of the accident, the effect of spray function on ^131-135I is significant. The release amount of iodine to environment and dose become larger when the spray removal coefficient decreases. Precursor nuclide decay has little effect on the dose results. The doses at exclusion area boundary and low population zone under different situations meet the requirements of acceptance criteria. The calculation results of source term and dose with the consideration of effective spray time and core instantaneous release are conservative.