Abstract: This paper deals with the following problems,1)The necessity of taking the influence of initial datum error into account when estimating the accuracy of a control network.2)Is it necessary to reestablish the principal network when its accuracy is lower than that of the secondary one?For the first problem five examples have been given to show the importance and to negate the traiditional requirment that the influence of the initial datum error must be much less than that of the observation error,when establishing a control network.As for the second problem,two measures have been proposed,i.e.to compensate low accuracy of the principal network by high accuracy of the secondary one and to change the configuration of the network using an appropriate observation accuracy.It is believed that the reestablishment of the principal network can be avoided.