According to the diagnosis of X-ray polarization spectrum in laser-produced plasmas with wavelength of 0.5～0.8 nm, a new pratical polarized spectrometer is designed and manufactured based on spatial resolution. Two pentaerythritol (PET) flat crystals are taken as dispersive elements, one is set in the parallel channel and another is installed in the perpendicular channel. The imaging plate with effective area of 30 mm×80 mm, is employed to receive the signal, and the optical path is about 240 mm from the source to the detector via the crystals. The X-ray spectrum emitted from the aluminum plasmas was recorded with imaging plates. The helium-like spectral line and lithium-like satellite line and their polarizations were calculated. The reason causing negative polarization is analyzed. These experimental results show that the measured value of the X-ray polarization spectrum matches the theoretical value well, and the polarization spectrometer is good for X-ray diagnoise of polarization spectrum in laser-produced plasma.