Abstract: Vector field data largely emerges in scientific and engineering computing, but the deficiency of powerful visualization technique for complex vector data sets causes the inefficient understanding and utilization in some research fields. Based on analyses of features of spot noise method and unsteady grid, time varying vector fields, a new technique, the unsteady spot noise, is proposed for visualizing 2 dimensional unsteady grid, time varying vector field. The new method is used mainly to solve the problems caused by varying grid and insufficient time accuracy in data. Implementation on data from numerical simulation of inertial confinement fusion has produced satisfactory result, and shown that the method is an effective visualization method for complex vector data.