The contact angle of lotus, canna, green poplar, grape and pumpkin were 150.6o, 135.5 o, 110.4 o, 101.3 o and 94.8 o respectively, five kinds of plant leaves were adhered to rectangular box by double-sided adhesive tape, which were called miniature boats. Miniature boats have super large loading capacity on water surface through the experimental measurements, loading capacity and water dimple depth increases with contact angle. Through mechanical analysis, the paper established mathematical model of loading capacity, comparing the measured values and measured values of loading capacity, the error ratio of loading capacity is about 4.0-6.1%. The loading capacity is made up of buoyancy and surface tension, percentage of buoyancy and surface tension in the loading capacity is affected by the contact angle and geometry size of miniature boats.