An single fiber scanning endoscopic imaging system was studied in this work. A single mode fiber is driven by a piezoelectric tube with a diameter of 1 mm. The light from the fiber illuminates the target area along spiral lines， while the scattered light is collected to build an image. It is known that the precise control of the fiber movement is significantly important to the imaging quality. Researchers have found that the fiber should return back to the origin after it finished the spiral scan. Since the system can not work for imaging during the fiber return period， it is important for the scanning fiber to retreat to the origin as quick as possible. This is the key point to improve the imaging efficiency. At the same time， the residual vibrations have a great influence on the imaging quality of the subsequent scan， especially at the central area. In order to address the above problems， a theoretical mechanical model was established to describe the fiber scan. And the forced vibration behavior was analyzed by solving the equations. Then an active braking scheme was proposed to stop the fiber damping by applying appropriate voltage signals to the PZT tube. The fiber braking simulations based on finite element analysis also confirmed the feasibility of the active braking. Finally， the actual experiments show that the fiber scanning imaging efficiency was improved from 0.629 to 0.897， an increase of about 1.4 times， by optimization of the braking signal. Simultaneously， the image distortion at the central area disappeared and the imaging quality was also improved. This study should be helpful for the ultra-fine multi-modal endoscopes， OCT， and industrial endoscope detection fields.