The waveplate is a usual but important component in optical system. Generally, λ/2 (or λ/4) waveplate is work at specifically wavelength. If the wavelength of the wave is not match to that of the waveplate, the phase retardation of wave would not π (or π/2). The broadband waveplate which the phase retardation is same in its bandwidth is widely used in spectrum shaping, laser tuning and optical communication. In this paper, an infrared three-stage waveplate is designed with the feature of wide band and high-resolution by the aid of computer simulation. The result of experiment turns to be high consistency with the design. The appropriate wavelength range of the waveplate is 1200～1650 nm. The central wavelength is 1390 nm. The phase retardation for λ/2 complex waveplate is 180.0°±3.6° and 90.0°±3.6° for λ/4 ones.