Identification of poisonous plants especially outdoor diet was practical for tourism in exciting outdoor travel. A new method called Poisonous Plants Retrieval System Based On the Mobile Device was proposed in this paper. The used mobile devices in this system were based on J2ME and the selected development platform was Eclipse. Firstly poisonous plants were classified into four main categories according to the subject categories of plants. Next, each of four main categories was classified into four sub-classes by analyzing the toxic parts or similar positions of plants. Then, to store the characteristics information of the subjects and poisonous position of plants, a symmetric two-dimensional array matrix form was developed. Finally the cell phone software retrieved known poisonous plant to help people make outdoor diet safe with high convenience.