Abstract: The end-effect of a linear Fresnel collector is very important to its optical performance. Based on a north-south mirror field, the equation for estimating the end losses was derived from analyzing the angle between incident sunlight and the tacking axis of a reflecting mirror. For latitude of 25°01′N, as an example, variations of the end losses on monthly average days, solstices and equinoxes were calculated and plotted as a function of the mirror-receiver distances, horizontal distances from the mirror to the receiver and solar time. The calculated results were verified by ray-tracing simulation and the end-effect compensation was discussed. The theory and results of this study are of actual significant on how to reduce end losses of linear Fresnel collectors.