Fused deposition modelling is a famous fabrication technique for engineering materials such as polylactic acid(PLA) which have lower melting temperature. PLA are semi crystalline aliphatic polyester thermoplastics and best alternative for petroleum based plastics. The printing parameters are one of the major concern for fused deposition modelling as it will affect the print properties. Infill density contributes to the changes on the mechanical properties. Infill density indicates the amount of materials the print and governs the amount of air gap between raster. This study aims to find out the optimal infill density of PLA and conductive PLA. For pure PLA, it shows an increasing trend in ultimate tensile strength as infill density increasing and achieved highest in 100% infill. However, there are decreasing trend present in conductive PLA as infill density increases. The tensile strength for conductive PLA are generally 2 times lower than the pure PLA printed due to presence of carbon.