An effective detection algorithm based on the randomness is devised in this paper for stego-webpages with different steganographies. The parts where secret information embedded in a webpage can generally be represented as two states, which can be described in binary code string. The randomness of the states varies a great deal depending on the webpage part carrying secret information or not. This paper presents a procedure to transform the binary code string into octal string to capture the randomness, from which some statistical features have been discovered. The theoretical description and proof are given that these features can be employed as a criterion to test whether a webpage contains secret information or not. Experiments show that this algorithm can effectively detect the stego-webpages based on letter changing in tags and invisible characters embedding.