Design of the preheat venturi scrubber has been performed using the process tool ASPEN Venturi by ASPEN Process Tool V 8.0- aspen one. Venturi scrubbers can be design using either the flowrate of gas at inlet conditions or the saturated gas flowrate. Various input parameter introduced in this research to be specified for sizing which included, Liquid to Gas ratio is kept 3.339 Litre/m³, Gas pressure drop is 4.9835 kPa, Entering gas temperature at standard conditions is 371.1°C and Liquid (water) volumetric flowrate is 0.000794 m³/sec. It is observed that higher values of Liquid to Gas ratio gives a higher pressure drop. As most commonly, Liquid and gas enters at converging section, or liquid can also be introduced from throat. As area decreases, gas velocity increases and pressure drop becomes higher which in accordance to Bernoulli's Equation. By keeping all the parameter constant likewise Liquid to Gas ratio and Gas pressure drop for all the process reading. At gas flowrate 0.2 m³/sec and 1.4 m³/sec, we get Throat Velocity 43.94 m/sec and 106.3 m/sec, Throat Diameter 0.07613 m and 0.13 m and Throat Length 1.6 m and 0.205 m, respectively. From graphical trend, it is proved that Gas flowrate is directly proportional to Throat velocity and diameter and inversely proportional to Throat length.