The invention discloses a passive pollutant flux sampler which includes a main body and a sealing member. A box body having a sampling port and a sampling chamber is formed by means of the main body and the sealing member in an enclosing manner. A sampling core is arranged in the sampling chamber. The sampling chamber is communicated with the sampling port. The sealing member encloses the sampling port at exterior of the sampling port so that the box body is matched with two plate surfaces forming to-be-tested corner gaps during detection to form a sealed L-shaped sample introduction channel by means of the sampling chamber and the sampling port through the two plate surfaces and the box body in an enclosing manner, thereby sealedly covering the to-be-tested corner gaps in the sample introduction channel. The sampler is simple in structure, is convenient to use, is free of geographic restrictions and can be used without professional operators, greatly reduces work load and cost of sampling and can be used for collecting the pollutants in a corner gap and material surface nearby it. The sampler can be matched with a sampler in the prior art to obtain accurate pollutant dissipation flux in the corner gap, thereby increasing the accuracy of measurement on the whole pollutant dissipation flux of a material.