For ultra-deep reservoir

the higher formation temperature and fracturing pressures lead to the limitation of pumping equipment in hydraulic fracturing. The paper focuses on the breakdown pressure and acoustic emission(AE) monitoring in large-scale hydraulic fracturing laboratory experiment with 762 mm×762 mm×914 mm in cement sample size by cycle and general injection. The test results show that: (1) Initiation pressures can be reduced on cyclic injection relative to general injection. Cyclic injection can bring about fatigue

which like the behavior of rock under uniaxial and triaxial cyclic loading. (2) For spiral perforation completion wellbore

the hydraulic fracture initiation only starts from the weakest perforation. Once the fracture is initiated

the other perforation holes are hard to reopen. The fracturing distance and cluster spacing should be chosen reasonably in hydraulic fracturing

to optimize the efficiency of reservoir stimulation. (3) The occurrence of the Kaiser effect before fracture initiation is the result of pore fluid diffuse to rock and cause the local rise in pore pressure

the failure modes can still be represented by Mohr circle. The results of the law of fracture propagation in cyclic injection

which is of great significance for the development of new fracturing technology.