<正>探讨了林木群体交配系统参数估算中理论值与观察值的差别，结果认为：对林木而言，通过种子分析估得的异交率［Ｔｏ］比实际的异交率［Ｔｅ］更高．即Ｔｏ＞Ｔｅ；另一方面，对两棵树或两个群体而言，估得的鼻交率之间的差距要比实际差距小，即：Ｔｏｌ—Ｔｏ２＜Ｔｅｌ—Ｔｅ２（假设Ｔｅｌ＞Ｔｅ２）。

The bias in estimating out crossing rate (T),one of the most important mating system parameters, was discussed in this paper.The conclusion is as follows: the exact value of out-crossing rate (or the theoretical value of outerossing rate)[Te] is iower than the one estimaled by seed analysis [To],i. e. To>Te, As a result,the estimated difference between two individuals or two populations is smaller than the exact one,i. e.if Tel>Te2,then To1—To2