Abstract: Using substorm AL index, substorm AE index and field-aligned current AF index in 2004, distribution of substorm AL, AE and AF onsets are studied with respect to substorm auroral onset. It is found that with auroral onsets being zero time, AL and AE onsets are mainly distributed between -5 and +6 minute, with only few exceptions between -9 and +9 minute. Field-aligned current AF onsets have a broader distribution from -8 to +7 minute. The average time differences of AL, AE, AF onsets are 0.5, 0.5, and -0.1 minute. The most probable AL onset is almost simultaneous with auroral onset, but the most probable onsets of AE and AF are about 1 min prior to auroral onsets. For those intense substorms, the onsets of AL, AE and AF approach to auroral onsets. For the five largest substorms, the onsets of AL and AE precede auroral onsets, suggesting during super substorms, substorm electric jet begin to increase before auroral breakup.