Abstract: Some special nuclear material (SNM) is inevitably deposited in the facilities (mixer, reactor) of nuclear material process line. Exactly knowing the quantity of nuclear material holdup is very important for nuclear material accountability and critical safety. The small angle-rotated emission tomography method was presented for SNM holdup measurement of spherical container. Because of other equipments exist at the left, right and back side of the container, so that the detectors can be put only in front of container for measurement. The nuclear material deposited in the spherical container can be looked as spherical shell source, which is divided into many voxels. The detectors scanning spherical shell source are rotated around the container at small angle at each layer to obtain projection data, with which deposited material distribution can be reconstructed by using least square (LS) method or maximum likelihood (ML) method. Based on these methods accurate total holdup can be obtained by summing up all the voxel values reconstructed. The measurement method for holdup in the spherical container was verified with Monte-Carlo simulation calculation.