In order to test the maximum electric field strength of electric multiple units（EMU） accurately

it is necessary to reduce the influence of background noise for the test.We proposed a kind of non-full shielding enclosure

which was designed based on electromagnetic shielding theory.The structure of this shielding enclosure is of multilayer composite material shield

and the material consists of metal layer

ferrite absorbing material

and pyramid absorbing materials

and the electric field strength of background noise could be decayed effectively.The suppression ability of non-full shielding enclosure could be detected by simulation software

and the electric field distribution of shielding box inside and outside space both could be obtained preliminarily.The results show that if background noise frequency is among 80 MHz to 2 GHz

the noise electric field strength will be decayed from 1 V/m to 0.25 V/m

and the value decreases averagely about 80% in different frequency points.If the wave source is set in other positions around EMU

the value will decay to 0.1 V/m and lower in different frequency points.The results verify the necessity of the shielding enclosure for the maximum electric field strength of train

and the feasibility of measurement.