Several fundamental image lossless compression methods are explained and researched comprehensively. With the relevance of adjacent pixel, an image lossless compression algorithm based on data multi-packet is presented, and four RLE improved algorithms for pixels which has same or similar gray value and a length code table compression algorithm for bi-level sequence are proposed in this paper, there is very good effect. Experimental results shows the algorithm has a better compression ratio than WinZIP, almost the same effect as WinRAR.