A heterogeneous offload version of Monte Carlo neutron transport has been developed in the framework of PATMOS prototype via several programming models (OpenMP thread, OpenMP offload, Ope-nACC and CUDA). Two algorithms are implemented, including both history-based method and pseudo event-based method. A performance evaluation has been carried out with a representative benchmark, sla-bAllNuclides. Numerical results illustrate the promising gain in performance for our heterogeneous offload MC code. These results demonstrate that pseudo event-based approach outperforms history-based approach significantly. Furthermore, by using pseudo event-based method, the OpenACC version is competitive enough, obtaining at least 71% performance comparing to the CUDA version, wherein the OpenMP offload version renders low performance for both approaches.