Predefined heater parameters are involved in self-tuned temperature control for plastic moulding. However the heater system transfer function depends on many external parameters, such as barrel filling level, type of plastic etc. This paper discusses a recursive least-square estimation of plastic moulding heater parameters identification. The real heaters have been estimated by recursive least-square method as 2nd or 3rd order transfer function having an error less than 7.5%. The optimal sampling time for the identification process of different heater cartridges has been obtained from Matlab simulation. The parameters of estimated model can be used in self-tuned temperature controllers for injection plastic moulding heater.