Abstract- In this experimental work, the mixing efficiencies of immiscible fluids were studied with finding out the mixing index of the fluids at the different velocities and with different Reynolds’s number. For finding the efficiencies of the immiscible fluids the pressure drop acts as an important role so as the pressure drop increases then the mixing efficiency of fluids increases. Also, pressure drop directly effects on to know the increasing the mixing efficiency. Also, residence time distribution is the key factor which is found in the mixing of the immiscible fluids in the static mixer which shows the time which remains in the static mixer to pass out the solution which is also important for the calculating the mixing efficiency of the fluids. The objective of the study is to design the static mixer for estimating the maximum mixing efficiency of immiscible fluids.