The utility model discloses a dull and stereotyped diagnosis ionization chamber of orifice plate formula collector, it has been solved, and there is air density balancing time problem longer relatively in solid collector among the prior art, has the air density of shortening balancing time, improves work efficiency's effect, and its technical scheme is: including ionization chamber housing, collector, entrance window, rear window and holding bracket, ionization chamber housing's bottom be equipped with holding bracket, ionization chamber housing's one end be equipped with the rear window, ionization chamber housing's the other end be equipped with the entrance window, ionization chamber housing and rear window, entrance window form sealed ionization chamber cavity, the collector ionization chamber housing's inside is fixed in through the support, the collector separate into first cavity and second cavity with the ionization chamber cavity, the collector on be equipped with a plurality of through -holes, first cavity and second cavity pass through the effect probability that the through -hole increases secondary electron and air.