The content of this report is based on the report of the IAU Commission 9 for 1996-1999 written by L.S.Mclean, (see Report on Astronomy 1996-1999, IAU Transaction Vol. 24A, P. 316-327), and with some more complementarity.
    The last decade of the 20th century was an unprecedented splendid time for astronomical telescopes and techniques, and more splendid achievements will be created since then. (1) Telescopes: Two 10 m Keck telescopes have been in operation since 1994 and 1996 in sequence. The first telescope of the four 8 m telescope project － ESO VLT got its first light in 1998, and the last one is going to get its first light soon this year (in 2000). One of the two 8 m telescopes of Gemini project and Subaru 8 m telescope  have both been completed recently. HET 9 m telescope is in its commissioning stage. LBT, which is composed of two 8 m telescope tubes, is going to be completed in the year of 2004. There are one 10 m telescope (copied from Keck) and one 9 m telescope (copied from HET) still in manufacturing. These telescopes have been equipped or are going to be equipped with advanced optical, infrared CCD cameras and spectrographs. For example, there are NIRSPEC in Keck, and FORS and ISSAC in VLT.  In sky survey projects: SDSS, 2dF, 2MASS and DENIS have been completed and all are in observation. LAMOST is under its active development. The concept design of VISTA has been started already. CalTech has started the concept design of the 30 m Extremely Large Telescope (ELT). ESO and NOAO have started the concept design of the 100 m telescopes respectively also. China and Britain have proposed some very good concept designs of ELT respectively too. (2) Detectors: The quantum efficiency (QE) of CCD now is 70%－80%for blue-optimized chips and 90% for red-optimized chips. The largest CCD mosaics which have been used in observation is 12k×8k. There are several CCD with dimension 8k×8k which have been equipped in telescopes. CCD mosaics with 20k×18k is under development. It is no doubt that the photographic plate has been replaced by CCD in astronomical observation now. In infrared band, 1k×1k HgCdTe CCD has been used in observation and 2k×2k is being developed. (3) Interferometry: There are several interferometer systems which have been in operation and have got some extensive astronomical results, for example, GI2T, COAST, IOTA, NPOI, PTI, ISI, SUSI, MIRA. Development of some interferometers is under way or nearly completed, for Example, CHARA, MRO, LBT. Especially two 10 m Keck and four 8 m VLT with some small telescopes will all form a very big interferometer array. The Keck interferometer is with a 140 m maximum baseline, and the maximum base line of VLT interferometer (VLTI) will be 200 m. Both will be in operation soon in the nearest future. (4) Adaptive optics: Adaptive optics is being equipped in many 3 to 4 m telescopes. Diffraction-limited optical and infrared imaging from ground is now obtained. Keck and ESO are both developing adaptive optics, which will be used in 8 to 10 m telescopes. All proposed 30 to 100 m Extremely Large telescopes will include adaptive optics too.