Abstract: The initial condition sensitivity leads to a limit for the prediction of mesoscale weather systems. The rapid growth of initial errors and associated mesoscale predictability depend on the features of flow. The generation of Meiyu heavy rainfall is the result of interaction of many different-scale weather systems. Therefore, there are different mechanisms for the formation and the sensitivity to initial condition of Meiyu heavy rainfall. The mechanisms of error growth for five different types of Meiyu rainfall are investigated. It is the larger scale cold air lifting, low level vortex, boundary layer cold pool, and gravity wave that play important roles in the error growth of Meiyu rainfall systems. They promote the scale growth of initial errors from small to larger scales in different ways. The perturbation simulations with random or systematic initial errors demonstrate that the initial errors can quickly reach its optimal scales in the systematic perturbation experiment. The cold air lifting controls the scale of error in the moving trough type of Meiyu rainfall, as a result, the scale of error is rather large and the predictability is rather high. The low-level vortex advection inthe Meiyu rainfall of the moving-out Southwest China vortex type and the north-trough with south-vortex type can offset the deviation within the vortex, and accelerate the transport of error energy from the small scale to large scale, and then the forecast skill of warm-season heavy rainfall is improved. The self-organizing rainfall system has a smaller saturation scale of error and lower predictability than those of the first two types of rainfall, because the immanent coupling mechanism of gravity wave and the cold pool can accelerate the dispersion of error energy, which results in the co-growth of errors at many scales. It is difficult for small scale error to reach its saturation in the non-organizing local rainfall systems, which is usually influenced by local terrain and thermal-dynamic conditions, and therefore it has the lowest predictability.The structure of error in Meiyu heavy rainfall is mainly dependent on the sub-weather systems, which play the most important role in the formation of Meiyu rainfall. The error in the moving trough type slants vertically along the front. Cold air intruding in the moving-trough and north-trough with south-vortex types leads to a prominent increasing of temperature errorat the mid-levels. The genesis of cold pool in the moving-out Southwest China vortex, north-trough with south-vortex, self-organizing, and non-organizing local system types results in a high momentum difference at the lower levels. During the later stage of all types of rainfall, there will be a large error zone at the upper levels, due to the transportation from the lower levels to upper levels.