To　study　the　statistical　meaning　of　the　time　parameter　t(63%)　in　the　Martin　empirical　formula,　we　took　Kunlun　25#　transformer　oil　as　the　liquid　insulating　dielectric　and　utilized　an　impulse　voltage　generator,　the　impulse　width　of　which　could　range　from　50　ns　to　1000　its,　along　with　the　corresponding　measuring　equipment.　The　relationships　between　the　breakdown　voltage,　the　breakdown　time　lag　and　the　discharge　probabilities　were　acquired　through　experiments　under　impulses　with　quasi-uniform　field.　The　results　show　that　the　discharge　probabilities　of　different　voltage　levels　under　the　fixed　impulse　waveform　and　the　breakdown　time　lag　under　the　same　voltage　level　both　could　be　well　fitted　to　the　three　parameter　Weibull　distribution　functions,　whose　shape　parameter　was　a　constant　only　correlated　to　the　electrode　geometry.　Meanwhile,　on　the　basis　of　the　Weibull　distribution　functions　and　corresponding　impulse　waveforms,　we　defined　the　effective　duration　and　show　the　statistical　meaning　of　the　time　parameter　t(63%).