The invention discloses a dynamic measurement system for the blade tip clearance and relates to the technical field of engines. The dynamic measurement system for the blade tip clearance comprises a capacitive sensor and a capacitive sensor signal-processing structure. The capacitance sensor is arranged on the casing of an engine. The induction terminal of the capacitive sensor is lower than the inner surface of the casing of the engine. A to-be-measured blade tip clearance is formed between the inner surface of the casing of the engine and a blade tip. The rotor of the engine is in normal operation. The to-be-measured blade tip clearance is dynamically changing. The capacitive sensor transmits an induction signal to the capacitive sensor signal-processing structure. The capacitive sensor signal-processing structure is used for processing the signal transmitted from the capacitive sensor. The system is simple and compact in structure, and the measurement of the system is realized in the non-contact mode. Therefore, the interference of the system on the jet flow field of the engine is reduced. The requirement of the on-line dynamic measurement on the blade tip clearance of the engine can be met.