Organizations’ operational data constructs the major data source for their data warehouse. The exponential development of WWW has made Internet an immense database containing all kinds of information with various types of data structures. Organizations are increasingly interested in capturing web data into their data warehousing systems to enlarge their data source for decision supporting, therefore improving accuracy and effectiveness of their decision making. This research thoroughly analyzes the data value of web data to data warehousing as well as business decision making, discusses the feasibility and potential problem of loading web data into data warehouse system, and provides a framework for evaluating web data for data warehousing purpose. Web data analysis and evaluation is regarded as a prerequisite for Web Integration - a breakthrough approach in furnishing data warehouse input: extracting, scrubbing, transforming web data and loading it into data warehouse systems to support organization decision making.