Abstract: Aimed at the simultaneous wireless information and power transfer (SWIPT) system with the intelligent reflecting surface (IRS) assisted, considering the imperfection of the channel state information, a beamforming algorithm based on the Bernstein-type inequality is proposed. Chance constraints were introduced to measure the channel uncertainty, and the transmitted power was minimized under the SINR constraint and the reflecting phase constraint. An external alternating optimization algorithm was developed to decouple the reflection phase and the beamforming vector. The non-convex chance constraint was approximated by the Bernstein-type inequality. For the unit module constraint, the reflecting phase was updated in the internal algorithm. MATLAB was used to verify the effectiveness of the algorithm. Numerical simulation results show that the IRS-assisted SWIPT system has the ability to reduce transmission energy and better anti-jamming capability.