In this paper, a brief review on the preparation of copper nanoparticles (Cu-NPs) is discussed which highlighted more on the green biosynthesis route. Copper nanoparticles have been proved by numerous of researchers on their capability to be used in wide range applications due to their unique properties apart of a low cost metal compared to the noble metal nanoparticles. Nowadays, green biosynthesis method has been favoured among researchers especially those study related with biological applications due to its simple, non-toxic and environmental friendly as compared to the physical and chemical method. Even though some of the green materials have both functions which act as stabilizing agent and reducing agent in the preparation of Cu-NPs, however, some of them need a booster which also must be a green material. So, ascorbic acid which is vitamin C that has been proven with its capability to act as stabilizing and reducing agent in most of previous studies also included in this short review.