This paper mainly describes the key problems in the precision forging of large and complex-shaped light alloy components. By means of a developed technique, several magnesium alloy and aluminum alloy forgings have been produced successfully. Due to the different shapes of the forgings, a scheme of isothermal forming and the use of a female die has been adopted and a method in which plastic mats exerting die-locking pressure are used, has been proposed. According to the geometric shape and size of the forgings, local loading techniques and diffluence theory have been employed, which can effectively reduce the forging pressure, improve the die filling capacity and ensure the manufacture of high quality forgings.