Supeova 1987A is a core collapse supeova in the Large Magellanic Cloud,inside which the product is most likely a neutron star.Despite the most sensitive available detection instruments from radio to γ-ray wavebands being exploited in the pass thirty years,there have not yet been any pulse signals detected.By considering the density of the medium plasma in the remnant of 1987A,we find that the plasma cut-off frequency is approximately 7 GHz,a value higher than the conventional observational waveband of radio pulsars.As derived,with the expansion of the supeova remnant,the radio signal will be detected in 2073 A.D.at 3 GHz.