Take radiation sensitive reference plant-pinus massoniana as an example, by constructing three-dimensional model of radioactive source term, three-dimensional model of pinus massoniana morphology and biology, mathematical and physical model of pinus massoniana external exposure dose evaluation to calculate external exposure absorbed dose rate conversion factor of pinus massoniana by writing the program code on Monte Carlo simulation platform. Then external exposure absorbed dose of pinus massoniana can be obtained and a method of pinus massoniana external exposure absorbed dose evaluation based on the simulation model can be constructed. It provides a method of high accuracy for pinus massoniana external exposure absorbed dose evaluation, and provides a reference solution for other reference plants and study of human body external exposure absorbed dose evaluation. At the same time, it can accumulate necessary information and experience on refer biology model, dose estimation and mathematical simulation technology, etc. It can provide a technical support for surrounding environmental radioactive evaluation of nuclear submarine force and the local plant and other nuclear units in our country in further.