The 2021 International Conference on Signal Processing and Machine Learning (CONF-SPML 2021) was held online from November 11 to 16, 2021. The accepted papers were published in IEEE CS Conference Publishing Services (CPS) (ISBN: 978-1-6654-1734-1). Prof. Aydogan Ozcan from UCLA, Prof. Tharmalingam Ratnarajah from University of Edinburgh, and Prof. Kim, Hosung from University of Southern California have given keynote speeches on related topics of deep learning, radar, motion synthesis, and retrospective correction. Also, we invited authors of qualified papers to deliver oral presentations at the online conference. 5 authors have presented their studies of action recognition, machine learning, face analysis, algorithm of graphic design, and active equalization topology. Questions from the audience were collected and answered by the presenters. This conference provided the participants with good opportunities to exchange ideas and build networks, and it will lead to further collaborations between both universities and other societies.