MgxZn1-xO is a promising material for developing solarblind ultraviolet(UV) photodetectors. However, the control of the MgZnO quality and the phase separation with increase of Mg in MgxZn1-xOO alloy is still a difficult problem. Up to now, no reports that the cutoff wavelength is at 273 nm have been found for the photodetectors based on MgZnO films. In this paper, cubic MgxZn1-xOO thin films are grown on quartz and sapphire substrates by Radio Frequency(RF) magnetron sputtering and Metal Organic Chemical Vapour Deposition(MOCVD). The MetalSemiconductorMetal(MSM) structured MgZnO photodetectors are fabricated based on the films. Results from spectral analysis shows that the photodetector exhibits a peak response wavelength at 225 nm with a cutoff wavelength of 230 nm, and the cubic phase MgZnO alloy with 255 nm absorption edge is finished by LPMOCVD and the MSM devices exhibit the peak energy at 250 nm with cutoff wavelength of 273 nm, which lies in the solarblind spectrum range(220~280 nm).