The turbine is a heart of power generation in a hydro-electric power system. A variety of different turbines are available for the purpose. The common types of Hydraulic turbines are; Pelton, cross flow, Francis, Kaplan, and propeller turbine. However, using conventional turbines for low head and flow rate (i.e. micro hydropower) applications is not economically feasible. A low-cost alternative is to use pump as turbine. In this paper, collect and review existing Pear reviewed articles from (Scopus, google scholar, umbrella, etc.) that are directly related to pump running as a turbine from the year (2014 to 2019). Theoretical, numerical, and experimental investigations are considered. Performance improvement techniques for PAT are summarized and research gaps in related works are identified.