Abstract: There may be mutual interference between adjacent particles on uranium particle isotope ratios analysis by secondary ion mass spectrometer (SIMS). The influences of distance and measurement order were investigated for U350 and U0002 uranium isotope ratios analysis with IMS-6f SIMS. When the distance was over 22 μm for U350 and 35 μm for U0002 under the conditions of this study, the measured results of ²³⁴U/²³⁸U, 235U/238U and 236U/238U of particles were in good agreement with the certified value. The poorer particles would be interfered severer than the richer ones under the same distance, and the safe distance is more farther for the poorer particles. The later measured particles would be interfered severer than the former ones when particles were analyzed one by one. The smaller, loser and thinner particles would be interfered severer than the larger and denser ones. Whether the linear combination coefficients of K₄(²³⁴U/²³⁸U)、K₅(²³⁵U/²³⁸U) and K₆(²³⁶U/²³⁸U) values were equal, and could be used to identify “mixed particles”, particle isolation with micro-manipulation was effective for eliminating neighboring particles interference. These results will provide references to adjacent uranium particles analysis by SIMS, so as to discover, handle and eliminate the suspected mixed particle data.