Roughness cannot be ignored as feature sizes shrink with Moore's Law, since it has potential to influence the device's performance. The roughness is usually described by line edge roughness (LER) and line width roughness (LWR). LER is the deviation of a feature edge from its ideal shape and is defined as three times the standard deviation, the deviation from the average line width is defined as LWR. For a certain critical dimension (CD) and pitch, there are many factors that can contribute to the roughness in the lithography process, such as source, mask optimizations, photoresist types and its processing, etc. An in-depth insight of the roughness formation mechanisms is essential to improve LER.This study employs photoresist process simulation to analyze LER, offering an efficient alternative to silicon data collection. Simulation analysis is carried out to examine the key factors influencing LER, including quencher concentration, photoacid diffusion length, PEB temperature. Concurrently, the study also delves into the impact of photoresist resin molecular composition and the development process on roughness. By using simulation to understand and predict roughness, the research provides insights into optimizing lithography parameters, thereby improving process stability and minimizing roughness formation.