English teaching observation, which has long been a common practice in different levels of schools,is beneficial to both observers (visiting teachers) and the instructor (the visited teacher). This paper covers the benefits and importance to both parties, especially those to the observers. Carrying out observation properly and effectively, we must master some techniques, ways and steps. There are two broad approaches to class visiting, qualitative and quantitative. Among qualitative approaches the “limited or selected ethnography or recording” seems tobe more practical; among qualitative ones, the SCORE method is focused on in this paper. Of the three observation ways, peer observation is described in detail: regarding observation, detailed descriptions are given of the three stages-preobservation, observation and postobservation. Some points to be paid attention to also are discussed in this paper.