In the past decade, many database computer (DBCs) have been proposed to use parallel architecture to support processing of database modelled by various data models. The design of a database computer to support database applications is a complex decision-making process. It involves many choices and combinations of choices for various parameters. Simulation techniques have been shown to provide reasonable accurate and useful performance evaluation with good flexibility. In this paper, we present the design and implementation of a Database Computer Architectures Performance Evaluation System (DACPES). DACPES is a simulation tool which can be configured to evaluate a class of parallel DBCs which have shared-nothing architectures, use data flow query processing strategies, and support object-oriented databases. DACPES can be used to simulate concurrent multiple query processing in a parallel DBC under varying conditions. The functions and design issues for each of the modules of DACPES are discussed and a case study of the evaluation of an Object Flow Computer using DACPES is presented.