The influence of laboratory wastewater properties on heavy metals treatment efficiency by the chemical precipitation included aluminium sulphate (Al2(SO4)3) and poly aluminium chloride‬ (PAC) using a stepwise multiple regression method. The laboratory wastewater properties showed high acidity approximately 0.75 and a highly turbid approximately 667.41 NTU that TSS (705.48 mg/l), COD (480.00 mg/l) and heavy metals such as Zn did not exceed the standards while Cu, Mn and Cr have levels exceeded the standards. Aluminium sulphate (Al2(SO4)3) coagulant has treatment efficiency for reducing heavy metals at a pH of 9 to 73.62%, 99.94%, 98.43%, 68.76% and 99.25% for various heavy metals (Cu, Fe, Mn, Zn and Cr) respectively with original laboratory wastewater properties that parameters of laboratory wastewater include TSS, BOD and pH having the highest influence on heavy metals treatment efficiency. The parameters of laboratory wastewater having the highest influence on heavy metals treatment efficiency when using poly aluminium chloride‬ (PAC) were pH, COD, DO and BOD when at a pH of 9 has treatment efficiency for reducing heavy metals to73.67%, 99.94%, 98.45%, 69.76% and 99.26% for various heavy metals (Cu, Fe, Mn, Zn and Cr) respectively.