A new 3-D Virtual Environment (3DVE) system named 0"QuViE/P" has been proposed in this paper, which can greatly enhance the quality of service (QoS) that users actually feel as good as possible, when the resources for computers and networks are limited. To do this, therefore, we focus on characteristics of the user's perceptual quality evaluation on 3-D objects. In this paper, we propose an effective QoS control scheme that introduces a relationship between system's internal quality parameters and user's perceptual quality parameters. This scheme can appropriately maintain quality and functions for users and is expected to drastically improve convenience when using 3DVE under the situation that resources are limited. Experimental results obtained from using a prototype of QuViE/P show effectiveness of our scheme as follows: Even when computer resource is reduced to 30% of the required amount, our proposed scheme can preferentially keep quality of important objects. Moreover it continues to provide quality and functions that user requires. Whereas in traditional QoS control scheme, objects of importance disappeared in similar situation.