Background Forests are the important component of terrestrial ecosystems and provide a variety of benefits for human. The assessment of forest ecosystem services has become a bridge linking human society and the natural environment.

Methods Based on the forest resources data in Liaoning province in 2017, we used the national standard specifications of the People's Republic of China "Specifications for Assessment of Forest Ecosystem Service in China" (GB/T 38582-2020) with the distributed measurement method to assess the services of soil conservation, forest nutrition retention, water conservation, carbon fixation and oxygen release, purification of atmospheric environment, in the Liaoning province. Grey relational method was used to analyze the influencing factors.

Results 1) The amount of soil conservation in the forest ecosystem of Liaoning province in 2017 was 24 846.82×10⁴ t; a total of 2 198.03×10⁴ t of fertilizers was preserved; the amount of forest nutrient retention was 59.00×10⁴ t; water conservation was 208.20×10⁸ m³; carbon fixation was 1 938.55×10⁴ t; oxygen release was 4 440.79×10⁴ t; the forest ecosystem provided 3.89×10²⁵ negative ion and absorbed 79.32×10⁴ t of gaseous pollutants, and retented 10 153.67×10⁴ t TSP, the masses of retented PM₁₀ and PM_2.5 substances were 2 164.40×10⁴ kg and 613.12×10⁴ kg respectively. 2) The service function of forest ecosystem generally presented the distribution pattern of mountainous area in eastern Liaoning > Northwest area > The coastal area of central and southern. Dandong, Fushun and Benxi had higher services and made proportion of more than 40% services, while Shenyang, Jinzhou and Panjin have lower services. 3) The factor with the highest degree of correlation with ecosystem service was precipitation (0.779 7-0.819 9), and the correlation between climate factors and service functions was higher than policy factors and socio-economic factors.

Conculsions This study can provide a scientific basis for scientifically carrying out forestry ecological projects in different regions of Liaoning Province, timely adjusting the direction of forestry development, and designing the path to realize the value of ecological products.