Abstract: General coherence factor weighted algorithm has been introduced to synthetic aperture imaging to increase the contrast,but its calculated amount is huge and the contrast can be improved limited.A method named space general coherence factor weighted algorithm was proposed,in which,the coherence factor is calculated according to the coherence among images constructed with single element transmissions,and then the resultant factor is used to weight the images to get final image by space synthesis.Simulations to points object and speckle object pattern using field II show that the calculated amount of the method is reduced to 1/N(N is element numbers of the array traducer), and compared with general coherence factor weighted algorithm,the SNR of the image to point object is increased by 7 dB.The contrast of the image to sound-absorbing speckle is increased by 3.5 dB.The method can increase the speed of imaging and improve the image quality.