Abstract: The PH₃ concentration in and outside packages of strips in a sealed plastic tent were determined. The effects of 3 kinds of package pattern (bale sandwiched with boards, corrugated cardboard box and corrugated cardboard box with plastic lining) on penetrability of PH₃ were also compared. The results indicated that the concentration of PH₃ in the tent reach the maximum value between 24-36 hours after fumigating and then dropped slowly. The PH₃ concentration in bales sandwiched with boards and corrugated cardboard boxes changed in the wake of that in the surrounding atmosphere. However, the PH 3 in corrugated cardboard boxes with plastics lining took 72 hours after applying pesticide to approach its maximum concentration at a lower level and was harder to be dissipated by ventilation compared with the other two package patterns.