Abstract: Isotope production is one of the main uses of research reactors, providing various types of radioisotopes for medical, industrial, scientific and other applications. In general, the higher the neutron flux level of a research reactor, the more favorable it is for radioisotope production. For the rod type targets commonly used in high-flux fast neutron research reactors, it is necessary to accurately calculate the neutron flux levels and isotope productions of the targets when evaluating the feasibility of the isotope production program for research reactors. SARAX program is an advanced reactor neutronics analysis and calculation system independently developed by the Nuclear Engineering Computational Physics Laboratory of Xi’an Jiaotong University, which mainly includes the cross section generation module TULIP and the core steady-state analysis module LAVENDER. Previously, the fuel management function of irradiated targets was initially developed in the version of SARAX-493 for the High-Flux Engineering Test Reactor (HFETR), but due to the high degree of customization, it was unable to meet the design and analysis needs of high-flux fast neutron research reactors. In order to meet the needs of isotope production calculation of rod type targets in high-flux fast neutron research reactors, this paper developed the isotope production calculation and target loading function of rod type targets based on the neutronics analysis program SARAX. Firstly, the reaction cross section and shape factor of the target rod region were generated by TULIP. Then, the flux reconstruction of the irradiated assembly was carried out by LAVENDER after neutron transport calculations by the modulation method, and the fine neutron flux distribution of the target rod within the assembly was obtained. Finally, the isotopic distributions of the target rods were obtained by the burnup calculations of the target rods by the ERICA module invoked by LAVENDER. The validation calculations were carried out with a certain high-flux fast neutron research reactor as the object of calculations and compares the results of the calculations with those of the equivalent modeling of MCNP, specifically including microscopic reaction cross sections, neutron flux density, isotope productions of target rods. The change in atom number density of the target rod from the first cycle of the core to the second cycle of the core was then calculated to test whether the target loading function was satisfied. The results show that the SARAX program has good accuracy in calculating the neutron flux density and isotope production of rod type targets, and is capable of realizing the target loading function. Different irradiated assemblies will be irradiated in the reactor for one year, and the calculation results of MCNP will be used as reference values, in which the relative deviation of the neutron flux density of the target rods calculated by SARAX is less than 4.2%, and the relative deviation of the isotope production is less than 7.6%.