The present invention discloses an optical viewfinder of a camera having the function of taking photographs, and the viewfinder comprises an objective module, a base, an eyepiece module and an upper casing. The objective module and the eyepiece module are fixed onto the front end and rear end of the base respectively and the upper casing is connected between the objective module and the eyepiece module and disposed in the middle section of the base. The simple structure of the invention is designed according to the principle of optical reflection and features a high resolution, an easy installation, and a convenient production, and the optical viewfinder is extensively used for cameras to substitute a high-cost electronic LCD screen.