Recent observations have revealed the Crab shows strong gamma-ray flares through synchrotron radiation whose maximum energy is around 370MeV with time-scale around 8 hours. Surprisingly, the observed energy is beyond the maximum energy of synchrotron photons radiated by electrons accelerated in MHD magnetic field. Although there are already some theoretical models which considered magnetic reconnection with an incredibly large spatial scale in Crab pulsar wind nebula, the origin of the flares is still controversial. In this presentation, we propose a new theoretical explanation of the Crab gamma-ray flare. Instead of considering phenomena in pulsar wind nebulae, we consider the double tearing mode (DTM) magnetic reconnection in a pulsar wind region. We obtained the evolution of DTM using resistive relativistic magneto-hydrodynamic simulations, and computed synthetic synchrotron spectra in the explosive reconnection phase. We found the variability of the Crab nebula/pulsar system, seen as flares, can be naturally explained by the DTM explosive phase in the striped wind. Our results also indicate that, in order to explain the Crab gamma-ray flare by DTM in the wind region, the magnetization parameter \sigma should be around 10^5 and the wind Lorentz factor be around 300.