Modelling and simulation of injection moulding process is an important techniques that shortened production cycle time with improved productivity for defect-free parts. This technique is more suitable for micro-injection moulding (µIM) process, likely defects during production ca be predicted. Therefore, this study aim to investigate the effect of runner dimension on the quality of moulded part. Solidworks plastic simulation software was used for mould cavity filling analysis of ASTM D638-10 Type V. The dimensions of the runner and the injection point are 0.5 mm, 0.8 mm, 1 mm and 2 mm. Weld line, sink mark and air trap were investigated. In addition, analytical model for prediction of melt pressure as a function of both melt filled distance (x_o) and the temperature is developed. The theoretical model and simulation software are useful for investigations of defect-free parts in µIM process.