Most research works on web retrieval latency are object-level based, which we think is insufficient and sometimes inaccurate. In this paper, we propose a fine grained operation-level Web Retrieval Dependency Model (WRDM) to provide more precise capture of web retrieval process. Our model reveals some new factors in web retrieval which cannot be seen at object level but are very important to studies in the web retrieval area. Categories and Subject Descriptors C.2.5 [Computer-Communication Networks]: Local and WideArea Networks – Internet; C.4 [Performance of Systems]: Modeling techniques. General Terms: Measurement, Performance