Abstract: The critical contact gap for the initial movement of columnar vacuum arcs is a symbolic physical metric, indicating the evolution of the high-current vacuum arc movement in the transverse magnetic field（TMF）contacts.This parameter has an important influence on the high-current breaking performance of vacuum circuit breakers equipped with TMF contacts.At present, there are limited research on the factors affecting the critical contact gap for the initial motion of columnar vacuum arc during high fault current interruptions in TMF contacts.This paper focuses on the expe-rimental study of the effects of slotting mode in TMF contacts, arcing duration, and arc current on the critical contact gap for the initial movement of columnar vacuum arcs.Results show that, within the arcing time range of 0～10 ms and current values of 5～31.5 kA,the initial columnar vacuum arc in the three kinds of TMF contacts have a tendency of longer stagnation when the arcing onset is closer to the current peak.The critical contact gaps for swastika-type（CuCr40）,spiral-type（CuCr25）,and curved swastika-type（CuCr50）TMF contacts are discerned to be 0.96mm, 1.1mm, and 1.7 mm, respectively.These findings provide a basis for a deeper understanding of the development and evolution of high-current vacuum arcs in TMF contacts.