An anti-interference microwave antenna includes a reference ground and at least a radiating source spacedly disposed at the reference ground to define a radiating clearance between the radiating source and the reference ground, wherein the radiating source is electrically connected to the reference ground to ground the radiating source so as to narrow a bandwidth of the antenna. When a electromagnetic excitation signal is received at a feed point of the radiating source, the bandwidth of the antenna is narrowed down to prevent any interference of the electromagnetic wave signal received or generated by the antenna in response to nearby electromagnetic radiation frequency or stray radiation frequency of the adjacent frequency bands.