给出一串已知的L系统符号串，以便从中寻找出能够通过L系统迭代生长复原的L基因组是目前L系统研究领域的逆向工作，为了能更好地进行逆向迭代，首先从研究符合串中的单符号统计规律入手，进而通过对在L系统的迭代生长中，单种符号数量发生有规律地变化进行的研究，提出了一些较有价值的符号统计关系式；然后在进行L符号串反演时，根据这些关系式，不仅能够缩小寻找逆向L基因组的范围，并能判定逆向L基因组的正确笥，从而为快速实现L系统符号串反演成L基因组，提供了较强有力的判据和可能性，而且这些关系式还 与其他搜索算法（如遗传算法）配合使用快的获得搜索结果。

There are many researches of simulative images or growth of biology with Lindenmayer system, but there are few researches on retrieved Lindenmayer gene set from a long Lindenmayer string. If Lindenmayer gene set can be retrieved from Lindenmayer string which can be obtained from image or growth of biology with other algorithms, the image or the growth of biology will be easier compressed or identified. Retrieving Lindenmayer gene set from a long Lindenmayer string which can be reverted with the set of Lindenmayer gene is researched in this paper. Base on iteration statistic laws of single symbol in Lindenmayer string, some valuable relationships of single symbol's quantities in iteration of Lindenmayer system are provided in this paper. The statistic laws of single 'growth' symbol can used for judge whether the Lindenmayer string is a iterated string quickly. Following to the relationships, the Lindenmayer gene set can be found out faster, and the relationships can judge the Lindenmayer gene set whether is true. First it can be got how many research sets from the count of single 'growth' symbol of the Lindenmayer string, then the length of string branch can be obtained with each set, and at last the Lindenmayer string can be judged whether it is a iterate string, the iterate gene can be brought out if it is a iterated string. The relationships can be used with other retrieving algorithm (ex. Iterate gene algorithm) to run better.