Abstract: This study developed an online platform with user-friendly interface and data entry for calculating the number of deaths in various diseases caused by fine particulate matter (PM_2.5). Six representative diseases, i.e., ischemic heart disease, stroke, lung cancer, lower respiratory tract infection, chronic obstructive pulmonary disease, and type 2 diabetes, were conducted to develop the online platform Mortality@PM (https://pm25.hhra.net) based on the formulae for calculating the number of deaths caused by PM_2.5 in different diseases and the interactive function of R shiny. With the three steps of input parameter setting, data uploading, and result calculation, Mortality@PM enables accurate and rapid assessment of PM_2.5-induced deaths from various diseases in different regions. The application of Mortality@PM facilitates rapid and standardized assessment of deaths from multiple diseases caused by PM_2.5.