Flexible hybrid electronics (FHE), integrating high performance silicon chips with multi-functional sensors and actuators on flexi-ble substrates, can be intimately attached onto irregular surfaces without compromising their functionalities, thus enabling more innovations in healthcare, internet of things (IoTs) and various human-machine interfaces (HMIs). Recent developments on com-pact models and process design kits (PDKs) of flexible electronics have made designs of small to medium flexible circuits feasible. However, the absence of a unified model and comprehensive eval-uation benchmarks for flexible electronics makes it infeasible for a designer to fairly compare different flexible technologies and to explore potential design options for a heterogeneous FHE design. In this paper, we present AutoFlex, a unified evaluation and design framework for flexible hybrid electronics, where device parameters can be extracted automatically and performance can be evaluated comprehensively from device levels, digital blocks to large-scale digital circuits. Moreover, a ubiquitous FHE sensor acquisition system, including a flexible multi-functional sensor array, scan drivers, amplifiers and a silicon based analog-to-digital converter (ADC), is developed to reveal the design challenges of a representative FHE system.