High-velocity clouds (HVCs) were first detected by HI 21 cm emission in 1963, since then the nature of HVCs remains controversial although more than forty years has been pasted. In the last decade, with the observations of high resolutions, the developments of theoretical models and numerical simulations, there has been great progress in many aspects of the studies of high-velocity clouds, particularly for some special kinds and the all-sky surveys. In this paper, main progress is reviewed including the observational studies of the two kinds of newly-found CHVCs and highly-ionized HVCs as a whole or individually, the high-resolution observations of Magellanic Stream and Complex C which are the largest HVCs in Southern and Northern sky respectively, as well as the one and only convincing constraint on the distance of Complex A which is in the range of 4－10 kpc from the Galactic center. Some theoretical models and simulations trying to explain the origins of HVCs are introduced briefly. This paper will also give brief descriptions on how to constrain the galactic distances of HVCs using Ha emission lines and the so far failed efforts to find stars in HVCs.