The invention discloses a fast measurement system, which is used for rapidly measuring a capacitor group on each bridge arm of an H-shaped bridge. The measurement system comprises a single-phase alternating-current power supply, a first ampere meter, a second ampere meter, at least one adjustable capacitor group and a processor, wherein the single-phase alternating-current power supply is used for supplying electricity to two ends of the H-shaped bridge; the first ampere meter is used for measuring a main current value of the H-shaped bridge; the second ampere meter is used for measuring an unbalance current value of the H-shaped bridge; at least one adjustable capacitor group is connected to the capacitors of the capacitor group in parallel; the processor is respectively connected with the first ampere meter, the second ampere meter and the adjustable capacitor group, and is used for emitting a control signal to adjust the electric capacity of the adjustable capacitor according to the main current value and the unbalance current value; and the processor can adjust the electric capacity of the adjustable capacitor group according to the relation between the main current value and the unbalance current value, and can rapidly measure a deviation value of the capacitor group on each bridge arm of the H-shaped bridge in the adjusting process according to the change rule of the unbalance current value.