The high precision 3D laser scanner with the dual CCD technology was used to measure the original design sample of a siphon jet toilet. The digital toilet model was constructed from the cloud data measured with the curve and surface fitting technology and the CAD/CAE systems. The Realizable k-epsilon double equation model of the turbulence viscosity coefficient method and the VOF multiphase flow model were used to simulate the flushing flow in the toilet digital model. Through simulating and analyzing the distribution of the flushing flow's total pressure, the flow speed at the toilet-basin surface and the siphoning bent tube, the toilet performance can be evaluated efficiently and conveniently. The method of "establishing digital model, flushing flow simulating, performances evaluating, function shape modifying" would provide a high efficiency approach to develop new water-saving toilets. (C) 2011 Published by Elsevier B. V. Selection and/or peer-review under responsibility of the Organising Committee of the ICOPEN 2011 conference