Studies of Microflares and C

nal Explorer (TRACE) coordinated observations from 16:00 to 19:00 UT to study properties of microoares on AR NOAA #8340. Fortuitously, a C5.2 are occurred at 16:30UT in this active region. H and magne-tograph movies were obtained at BBSO; CIV 1550 A , FeIX 171 A and FeXII 195 A movies were obtained by TRACE; both with a cadence about 1 minute. In this paper, we concentrate on the study of magnetic properties of 70 CIV microoares, as well as their relationship to the C5.2 are. We obtained the following results: (1) We found two kinds of microoares: microoares of transient brightenings with a time scale of 1 to 5 minutes (impulsive events) and microoares lasting half an hour or longer (persistent events). 90% of the microoares are impulsive events. Most of the events in this category are associated with well deened magnetic neutral lines, but some of them are found in non-neutral line areas. All of seven persistent events are found at parasitic magnetic conngurations with inclusions of small magnetic ux within dominant magnetic ux of opposite polarity. (2) More than a third of the impulsive microoares occurred near the C5.2 are site indicating that a local instability is responsible for both the C5.2 are and microoares. This indirectly support the avalanche theory of are energy release, which predicts that a big are may be associated with many small ares.