The IEEE 802.11ax for Wireless Local Area Network (WLAN), one of the most important wireless networks, will be released in 2020. In recent years, ultra-high definition video service and real-time applications attract increasing attention. Therefore, the next generation WLAN (beyond IEEE 802.11ax): IEEE 802.11be task group (TGbe) was formally established in 2019, which regards achieving extremely high throughput (EHT) as its core technical objective. This article investigates and analyzes the key technologies of IEEE 802.11be, and further provides our perspectives and insights on it. Specifically, this article gives a brief overview on IEEE 802.11be, including the target scenario and technical objective, key technologies overview, and the standardization process. After that, we further investigate, analyze and provide perspectives on the key technologies of IEEE 802.11be including multi-band operation, multi-AP coordination, enhanced link reliability, and latency & jitter guarantee. To the best of our knowledge, this is the first work to investigate, analyze and provide insights on IEEE 802.11be.