The invention relates to a bladder volume measurement and calculation method under abdominal two-dimensional ultrasound. The method comprises the following steps that 1, the bladder is subjected to abdominal scanning, and a bladder two-dimensional image, namely, the median sagittal plane D1 is obtained through the ultrasound; 2, a probe is counterclockwise rotated by 90 degrees, and the maximum section, namely, the cross section D2 of the bladder median sagittal plane is obtained; 3, the probe is clockwise rotated by 45 degrees on the basis of the first median sagittal plane D1, and the maximum section, namely, the left slope D3 of the bladder median sagittal plane is obtained; 4, the probe is clockwise rotated by 45 degrees on the basis of the D2, and the maximum section, namely, the right slope D4 of the bladder median sagittal plane is obtained; 5, the center point Q of the median sagittal plane is positioned; 6, the median sagittal plane D1, the left slope D3 and the right slope D4 are measured; 7, the cross section D2 is measured; 8, the actual volume of the bladder is calculated according to a formula.