Logging harvesters represent a set of high-performance modern forestry machinery,which can finish a series of continuous operations such as felling,delimbing,peeling,bucking and so forth with human intervention.It is found by experiment that during the process of the alignment of the harvesting head to capture the trunk,the operator needs a lot of observation,judgment and repeated operations,which lead to the time and fuel losses.In order to improve the operation efficiency and reduce the operating costs,the point clouds for standing trees are collected with a low-cost 2D laser scanner.A cluster extracting algorithm and filtering algorithm are used to classify each trunk from the point cloud.On the assumption that every cross section of the target trunk is approximate a standard circle and combining the information of an Attitude and Heading Reference System,the radii and center locations of the trunks in the scanning range are calculated by the Fletcher-Reeves conjugate gradient algorithm.The method is validated through experiments in an aspen forest,and the optimized calculation time consumption is compared with the previous work of other researchers.Moreover,the implement of the calculation result for automotive capturing trunks by the harvesting head during the logging operation is discussed in particular.