Falling film heat exchangers have recently been widespread as a heat transfer technique for oily wastewater. Researching the characteristics of fluid mechanism for heat transmission is crucial. In this research, numerical models are applied to simulate the heat transmission and flow of falling film outside ellipse tube. In order to emulate fluid flow and heat transmission, the oily wastewater falling film is analyzed utilizing the VOF approach under circumstances of constant thermal flow. On the flow properties and heat transfer coefficient distribution of liquid film, the impacts of the input height, contact angle, liquid film flow rate, and oil content are examined. These computational outcomes are attained: (1) More so than film thickness, according to the simulation results, increasing liquid film flow significantly affects velocity;(2) One of the main causes of how oil concentration affects heat transmission is the complex disturbance process of liquid film and the force change around tube structure;(3) Around 40°, inlet height has the greatest impact on local heat transfer coefficient;(4) The overall heat transmission will deteriorate due to the hydrophobic impact brought on by increased contact angle.