The plant stem flow measuring instrument uses the heat dissipation probe method to measure the instantaneous stem flow density of tree trunks. It can continuously observe the sap flow of trees for a long time, which is beneficial to study the water exchange rules between trees and the atmosphere. It can also be used as an observation method to monitor the forest for a long time. Effects of ecosystems on environmental change. It has important theoretical guidance and application value for afforestation, forest management and forestry management.