a novel type of ince-gaussian (ig) beam, named as pig (ince-gaussian beam with phase difference) beam, based on the initial phase difference factor modulation between even mode and odd mode of ig beam is proposed. the pig beam is generated by the linear superposition of the even mode and the odd mode of traditional ig beam after the even mode being multiplied an exponential phase factor with an initial phase difference of φ. the modulation properties of the initial phase difference factor on spatial mode of the pig beam are mainly studied when other parameters are the same. numerical simulations and experimental results show that the pig beam changes from positive vortex state to negative vortex state when φ continuously increases from 0 to π. the vortex state is vanished when φ=π/2. as φ is equal to integer multiple of π, the switch from the positive vortex state to the negative vortex state is realized. as φ is equal to half-integer multiple of π, light traps of the pig beams can be accurately controlled to move on the oval orbit. the pig beam will provides an additional degree of freedom for micro-particle operation and beam micro-machining. © 2017, chinese lasers press. all right reserved.