The present invention relates to a multimedia retrieval system and a method thereof which is capable of performing a multimedia data retrieval among different systems using color histograms constructed with different color spaces and color quantization methods, in particular to a content-based multimedia retrieval system and a method thereof which is capable of retrieving multimedia data among different systems, by extracting or converting a color histogram of a query image or a color histogram of an image to be retrieved into a color histogram of the same color space and color quantization method each other, and using the extracted or converted color histogram.