Abstract: In this paper，the concept and the drawing mechanism of the L-systems is designed.Based on the single-formula of the L-systems，the theory of the pseudo L-systems are proposed which is the multi-formula，and meanwhile the randomicity of the edges is considered.The theory of the context-sensitive L-systems is also extended.When the controlling parameters are considered the pictures can be changed artificially.Here，much living and dynamic scenery is gotten.

Key words: fractal L-systems, turtle, randomicity, context-sensitive

摘要： 介绍了L-系统的概念以及作图原理，在单规则作图机制的基础上，提出了伪L-系统的多规则产生式机制，同时把边长的随机性引入到L-系统中，得到了较为理想的自然景物。将上下文相关的L-系统在理论上进行了扩展，把控制参数引入其中之后，可以使图像按照既定的构想发生变化，得到了更加逼真的动态自然景观。

关键词: L-系统, 导龟, 随机性, 上下文相关