The convex crystal spectrometer, consists of a convex crystal and CMOS camera which assembles CsI(Tl) scintillation, has been designed and fabricated to record X- ray spectra in the energy range of 1.84-7.38 keV by QTZ(1010) (2d=0.851 2 nm) X-ray crystal at one shot. The spectral resolving power was 880 at 2.375 keV, dynamic range of at least 1 000. This spectrometer has characteristics of online aiming, high resolving power, and wide energy range and less noise counts. At Shenguang-III laser facilities, soft X-ray spectroscopy from Titanium laser-produced plasmas was obtained by the spectrometer, main lines of Titanium ions have been identified in the excellent agreement with theoretical calculation and other experiment results. On the DIM of Shenguang-III laser facilities, the spectrometer can work stably and adapts to the over loading electron magnet pulse environment.