Sn1-xNixO microflowers self-assembled with nanopetals have been synthesized successfully with template-free hydrothermal growth method. Field-emission scanning electron microscopy results exhibit the flower-like architecture consist of nanopetals, which have lateral dimensions of 1-2 mu m with a thickness of similar to 100 nm. X-ray diffraction results show that all the samples possess typical tetragonal structure and Ni would occupy different positions (Ni-sn and Ni-i) with various concentrations. The bandgap of SnO tends to shrink firstly then widen after Ni-doping, which is caused by the sp-d exchange interactions and the Burstein-Moss effect. Meanwhile, PL and XPS measurements illustrate that tin vacancies (V-sn) and oxygen vacancies (V-o) were generated during the process of preparation and the Vsn as the origin of the ferromagnetism in pure SnO was verified by air-anneal experiment. In addition, Ni-doping can improve the ferromagnetism via enhancing the content of V-sn. This literature studies the ferromagnetism of novel SnO flower-like structure firstly and reasonably reveals the desired ferromagnetism originated from the V-sn. (C) 2017 Elsevier B.V. All rights reserved.