Tandem One-Dimensional Photonic Crystals (1DPCs) are employed to improve the photovoltaic conversion efficiency of the semitransparent organic solar cells and tailor the see-though colors of the devices. Transfer matrix method is employed to calculate the absorption in the active layer and transmission spectra of the devices. With these calculated data as inputs, the photovoltaic conversion efficiency and the see-though colors are calculated. It is revealed that an improvement of 24.4% in the photovoltaic conversion efficiency is achieved by tailoring the center wavelength of the bandgap of the top 1DPCs and bottom 1DPCs in the tandem 1DPCs. In addition, the see-through colors of the device can be tuned by tailoring the center wavelength of the bandgap of the top 1DPCs and bottom 1DPCs. Correspondingly, semitransparent organic solar cells with different see-through colors such as blue, green and red can be obtained. Compared with the single 1DPCs, tandem 1DPCs can lead to higher improvement in PCE and broader tunable range of the see-through color of the devices.