Bipolar forceps are a type of electrosurgical device (ESD) widely used for tissue welding in modern surgeries. ESDs have many advantages over traditional surgical tools including reduced blood loss, improved efficiency and lower surgeon fatigue. However, these devices suffer from tissue sticking and damage due to overheating which leads to poor tissue joint quality. The problem is potentially caused by uneven power distribution due to non-uniform compression applied by the bipolar forceps. In this study, the effect of compression force uniformity was investigated with an experimental setup to achieve a uniform and consistent compression force at the jaws of bipolar forceps. Comparative tissue welding experiments were conducted under both uniform and non-uniform compression force conditions with tissue mimicking material. In situ welding process parameters including compression force, electrical voltage, and current were collected and analyzed to understand the effect of compression force uniformity. The results indicate that tissue impedance is lower due to increased tool-tissue contact area; the electrical power is initially higher during the first few milliseconds. The experimental device developed in this study provides an important platform to understand the difference of tissue welding process under uniform and non-uniform compression force conditions.